If folding is not suitable for Yiddish texts or Biblical texts or ancient Greek texts or any other text then I suggest that the user of said text seriously considers not using folding.
Only very few foldings make sense to apply on a permanent basis. Think of casefolding for example. Such a folding is mostly useful for searches, where it is applied *transiently*.
Ideally, all searches are tailored in a language specific way, so that you can strike the right balance between convenience and false positives.
A./
