Sujato's translation of 'rational' for 'yoniso', is not the most rational choice, and neither is 'choice' for 'sankhāra'

rational defn.

From Oxford American Dictionary

ˈrashənl; ˈrashnəl

1. ra·tion·al

adj.

1) based on or in accordance with reason or logic

I'm sure there's a perfectly rational explanation

■ (of a person) able to think clearly, sensibly, and logically

Andrea's upset-she's not being very rational. See note at sensible 

■ endowed with the capacity to reason

man is a rational being

2) Mathematics (of a number, quantity, or expression) expressible, or containing quantities that are expressible, as a ratio of whole numbers. When expressed as a decimal, a rational number has a finite or recurring expansion

2. ra·tion·al

n. Mathematics a rational number

Derivatives:

rationality ˌrashəˈnalətē n. rationally ˈrashənl-ē; ˈrashnəlē adv.

Origin:

late Middle English (in the sense ‘having the ability to reason’): from Latin rationalis, from ratio(n-) ‘reckoning, reason’ (see ratio )

'rational' for 'yoniso' fails in all the important references

Take a look at how 'yoniso' is used in 450+ sutta occurrences, 

click the little arrows next to sutta ref. to show pali + english line by line.

Right off the bat, in the very first  AN 1 references that come up, yoniso as "rational" fails badly.
Basically, being "rational" (yoniso) leads to 7 awakening factors being developed,
and being "irrational" (a-yoniso) leads to 5 hindrances increasing in power.

On the surface, it seems true enough. 
But the problem is, it's too superficial. 
It would be like saying, all you have to do to be the best hitter in baseball is hit 40% of the balls safely and advance to first base or further.
True enough, but how do you actually do that? 

Similarly yoniso is doing much deeper operations that require samādhi (undistractible lucidity) and paññā (wisdom) than simply using one's intellect and reasoning. 
You're not going to be able to actually overcome the 5 hindrances and develop 7 awakening factors simply by having an intellectual theoretical grasp that is "rational". 
Other suttas references with yoniso make this very clear.

For example in other sutta references, developing paññā (wisdom) that realizes the steps that culminate in nirvana happens concurrently with yoniso manasikāra, 

showing that yoniso can not just be "rational", 

otherwise you'd expect 80% of educated humans to be arahants already if being "rational" was all it took.

translating 'yoniso' is difficult

I understand all the trickiness and issues, of why translating 'yoniso' is difficult.
Sujato does as well, but it's perplexing why he still choose 'rational' for yoniso.

Just to be different from the other translators?

That translation is rational on a superficial level,

but in my opinion highly irrational if the prime directive is to do no harm to the true Dhamma,

giving misleading impressions on the meaning of important terms.

Sure "wise attention" overburdens "wisdom" and how it maps to similar pāli words having to do with knowledge and wisdom, discernment/wisdom faculty, etc.
But at least it makes it very clear, that anytime wisdom is involved, that something deeper beyond intellectual understanding is involved, 

requiring samādhi and paññā to have direct experiential realizations. 

Thanissaro renders 'yoniso manasikāra' as "appropriate attention".
Bhikkhu Bodhi originally followed Nanamoli's "wise attention", 
later switched to "careful attention".

Those are vague, but at least it doesn't commit a huge problem of misleading the reader into thinking all one needs to do to realize nirvana is develop average intellectual reasoning ability.

The root problem here? 

TITWOW Syndrome : TITWOW = Translators Irritatingly Translate With One Word Syndrome.

Sujato put himself in a box thinking he has to use a one word translation for 'yoniso'.

He didn't like the option of creating a word like 'cause-wise',

or using bulkier multiword translations for every occurrence of 'yoniso'.

He didn't explain why. Obviously those are not ideal, but in my opinion,

better to be vague (if you choose one word translation route) or bulky (with multi word translation)  but clear in meaning than to satisfy some primal fetish of finding a perfect one word translation that doesn't exist in this case of yoniso;

 at the cost of seriously misleading readers, especially beginners, into thinking reason and intellect is all it takes to realize nirvana. 

There are lots of other problems as well, 

you can dig through the sutta references and see for yourself.

 'yoniso' in 450+ sutta occurrences

verdict on translating 'rational' for 'yoniso'

If you treat yoniso as having a few different meanings for a few different contexts,

then "rational" is probably valid for mundane situations (just those contexts).

But if you're using "rational" for all the different contexts,

then "rational" is "wrong" at worst, and at best, dangerously misleading readers into thinking all you need to realize nirvana is some modicum of intelligence and reasoning skills.

 Sujato's translation of 'choice' for 'sankhāra' is wrong

"choice" defn.

 From Oxford American Dictionary

chois

1.

n. an act of selecting or making a decision when faced with two or more possibilities

the choice between good and evil

■ the right or ability to make, or possibility of making, such a selection

I had to do it, I had no choice

■ a range of possibilities from which one or more may be selected

you can have a sofa made to order in a choice of over forty fabrics

■ a course of action, thing, or person that is selected or decided upon

this CD drive is the perfect choice for your computer example.

why it's wrong

san-khāra, literally co-activities, is just a slightly different form of karma,  'kamma', action.
And 'karoti' the verb form 'do' or 'act'. 
An action doesn't have to commit to a choice of several possibilities.
sankhāra as one of the five aggregates that comprise our sense of self, 
is an intention/volition (cetana) by means of the 6 senses (eye, ear, nose...mind). 
And intention is not obligated to commit to a 'choice'.

example 1: what if you don't want to choose?

For example, you might exercise your power to 'sankhāra' by having an intention to do nothing, 
an intention to "NOT CHOOSE";
the very thing Sujato has force fed you into committing yourself into every time he uses that as a translation.

example 2: what if you know exactly what you're going to do and no choice was involved?

For example, say you are skilled in jhānas and you want to go through jhānas 1 through 4 successively.
You already know how to do it, it's already a skill in your muscle memory,
you just simply issue a volitional action, an intention (sankhāra!) to act, to karoti, to do, and desired result happens.
You get first jhāna, second jhāna, etc.
You didn't choose between anything.
You know what actions you want to do, then you acted. There was no choice.
But according to Sujato, you had to make "choices" every little step of the way.

I really don't understand what Sujato is thinking

I understand that he obviously didn't like the existing translations for some important doctrinal terms, 
seeing them as vague, or cryptic, and unfriendly to casual readers of his translations.

But what I don't understand is why does he think it's ok to use clever single word translations that work in many contexts, but fail in the important ones? 
"volitional activities" (B.Bodhi trans. of sankhāra) sounds intimidating and complicated. But it's accurate!
"choice" is simple and friendly. But it's wrong!

Is it better to mislead the casual reader with a nice fluent translation into thinking they understand a misrepresentation of the Dhamma?
Sujato's translation of 'sankhāra' and 'yoniso' is like something bad Artificial intelligence would do.
Authoritatively give an answer that most people believe, sounds reasonable, works in many contexts, but fails in several important ones. 

Is it better to be correct but a little intimidating sounding?

Or simple, friendly, right 70% of the time but wrong on the more important 30% of the time?

To me, the choice is both obvious and rational.