I don't use zig, but it seems to me that functions can choose exactly which type of allocator they want to accept (just by changing the type of the allocator parameter), making his point invalid.
From what I have seen, people writing about linguistics do not usually bother specifying this distinction in this context. It is usually implied that an expression like "following a vowel" or "following a consonant" has nothing to do with orthography, but the actual phonetics. The orthography is not really considered a source of truth.
Their React example kind of points towards this: https://github.com/projectfluent/fluent.js/wiki/React-Bindin...
They provide a <Localized> component, which has an identifier and wraps a piece of markup containing the original:
Seems like the best of both worlds.