Literally physical, or metaphorical? parimukha (around the mouth), kāya (body, collection), kāya-sakkhi (body-witness), nirāmisā, rūpa

There are some words in meditation and jhāna context, it's debated whether they are literally referring to something physical, or just metaphorical.

How do we know for sure?

Do a digital search, dig up every occurrence and look at how it's being used.

Kāya in a meditation context, 

especially jhāna, always is referring to the meditator's physical body in the EBT. 

The only exception, in later canonical works, for example in KN Ps, kāya is expanded to refer to the mental body IN ADDITION to the physical body, not a mental body INSTEAD of a physical one.

In other words, kāya = both rūpa kāya (material form physical body) + nāma kāya (mental body). 

This is probably done in attempt to smooth out the contradictions and inconsistencies with Abhidhamma and EBT suttas. 

See MN 119 for example.

Lots more here: https://lucid24.org/tped/k/kaya/index.html

Parimukha as prelude to meditation

If we examine all the sutta occurrences here: pari-mukha:

Literal, spatial location near the mouth? Or metaphorical "in front of you"?

In the Vinaya talking about regulation of a monk's facial and chest hair, it's literal.

In meditation contexts, parimukha must be metaphorical, not physical.

Because it's not just breath meditation that refers to parimukha (where breath meditation and nostril/mouth make sense as a literal interpretation).

Parimukha satim, is also used when one is removing 5 hindrances, or doing metta meditation.

Both of those have nothing to do with the nostril!

So we can conclude parimukha must be a metaphorical meaning of "place in front",

similar to an English expression "focus on task at hand", or "con-front reality". 

It's not physical spatial location, it's a metaphorical meaning putting an important task "in front of you", making it your prime focus.

kāya-sakkhi (literally, 'body witness")

If we examine all the sutta occurrences: kāya-sakkhī:

It's not about the physical location, it's a metaphorical meaning of being a direct witness, 

realizing something directly, as opposed to hear say, or imagination.

Very similar to English eye-witness.

You don't have to physically see something happen to be an eye-witness.

A blind person for example can hear a distinctive voice and enunciation of a murderer, and that would be an eye witness account.

nirā-misā (literally, "not of the flesh")

A Literal physical interpretation, or metaphorical meaning?

Again, if you want to be an honest Buddhist scholar, you actually have to do your due diligence.

Do a digital search, look at all the occurrences.

See how it's being used.

At first glance, in a meditation context this seems to suggest or at least not oppose the interpretation that one must be in a samādhi where the mind is divorced from the 5 senses.

But if you study a few key suttas carefully, we can already see it can't be a formless state.

        SN ^36.31.1 - (3 types of pīti)
            SN ^36.31.1.1 – (s'-āmisā pīti / carnal rapture = 5kg )
            SN ^36.31.1.2 – (nir-āmisā pīti / non-carnal rapture = first two jhānas)
            SN ^36.31.1.3 - (nir-āmisā nir-āmisatarā pīti / surpassing non-carnal rapture = arahant)
        SN ^36.31.2 - (3 types of sukha)
            SN ^36.31.2.1 – (s'-āmisā sukha / carnal pleasure = 5kg )
            SN ^36.31.2.2 – (nirāmisaṃ sukhaṃ / non-carnal [physical] pleasure = first 3 jhānas)
            SN ^36.31.2.3 – (nir-āmisā nir-āmisatarā sukha / surpassing non-carnal pleasure = arahant)
        SN ^36.31.3 - (3 types of upekkha)
            SN ^36.31.3.1 – (s'-āmisā upekkha / carnal upekkha = equanimous-boredom)
            SN ^36.31.3.2 – (nirāmisaṃ upekkha / non-carnal equanimous-observation = 4th jhāna)
            SN ^36.31.3.3 – (nir-āmisā nir-āmisatarā upekkha / surpassing non-carnal equanimous-observation = arahant)

Nirāmisā upekkha, is defined as 4th jhāna.

But in MN 137, we see tha upekkha of 4th jhāna is equanimous toward all 5 senses of the body.

    MN ^137.4 – (rely on something superior to give up something inferior)
        MN ^137.4.1 – (rely on renunciate mental-joy to give up householder mental-joy)
        MN ^137.4.2 – (rely on renunciate mental-distress to give up householder mental-distress)
        MN ^137.4.3 – (rely on renunciate equanimous-observation to give up householder equanimous-observation)
        MN ^137.4.4 – (rely on renunciate mental-joy to give up renunciate mental-distress: use first two jhānas to give up renunciate mental-distress)
        MN ^137.4.5 – (rely on renunciate equanimous-observation to give up renunciate mental-joy: use 4th and 3rd jhāna to give up 1st and 2nd jhāna)
    MN ^137.5 – (two kinds of upekkha equanimous-observation)
        MN ^137.5.1 - (upekkha based on diversity/nanatta are 3rd and 4th jhāna)
        MN ^137.5.2 - (upekkha based on unity/ekatta are 4 a-rūpa attainments)

137.5.1 - (upekkha based on diversity/nanatta are 3rd and 4th jhāna)

Katamā ca, bhikkhave, upekkhā nānattā nānattasitā?	And what is equanimous-observation based on diversity?
Atthi, bhikkhave, upekkhā rūpesu, atthi saddesu, atthi gandhesu, atthi rasesu, atthi phoṭṭhabbesu—	There is equanimous-observation towards forms, sounds, smells, tastes, and touches.
ayaṁ, bhikkhave, upekkhā nānattā nānattasitā.	This is equanimous-observation based on diversity.

[Diversity (nanatta) of 5 sense fields connected to the mind is what’s abandoned when one enters dimension of infinite space. This also means that those 5 bodily senses are active in the four jhānas.]

Why would you be equanimous toward 5 senses if supposedly nirāmisā pīti and sukha physical happiness isn't possible since 5 senses don't exists in the first 3 jhānas?

Obviously the 5 senses are active in the 4 jhānas, and not in the formless.

So this is already enough to show nirāmisā ("not of the flesh") is not a literal interpretation in the 4 jhānas context.

Just as Kāmā (lust, sensual desire for 5 cords of sensual pleasure), is always placed in opposition to nekkhamma (renunciation), rather than formless samādhi.

Have you noticed Vism. and Ajahn Brahm school of followers interpret all of these cases above in the exact opposite way of what objective scrutiny reveals?

It's natural for humans to have confirmation bias.

But honest scholars objectively look at all the evidence, as opposed to cherry picking one or two suttas that support their favored position, and ignoring the rest.

Scholars with integrity, when confronted with incontrovertible evidence, will admit their mistake and conform their views with the truth.