When I was drafting my previous post, I realised that I wasn’t sure about the exact wording of the funeral/memorial sentence Rest eternal rest grant (unto) them, O Lord, and let light perpetual shine (up)on them.
The Latin original is Requiem aeternam dona eis, Domine, et lux perpetua luceat eis. Latin adjectives standardly follow the noun they modify (though word order in Latin is relatively free), so requiem (rest) aeternum (eternal) and lux (light) perpetua (perpetual). I searched online for an English translation. About half said rest eternal and light perpetual, and half said eternal rest and perpetual light. English adjectives standardly precede the noun they modify, but can follow them in certain circumstances, one of which is to produce an air of formality, perhaps because of the echo of Latin. (From a brief browse, no source switches word order mid-way: rest eternal and perpetual light or eternal rest and light perpetual.)
I noticed that the sources which use rest eternal and light perpetual tend to be Anglican/Episcopalian, and those which use eternal rest and perpetual light tend to be Roman Catholic. In fact, the Wikipedia article about this prayer says that Lutherans use the noun-adj order and Methodists use the adj-noun. I’m not sure what conclusion, if any, we can draw from that.