Pluralization of currencies like the baht and the ringgit
Solution 1:
I've never heard anyone use an ending 's' when describing Chinese yuan, Japanese yen, or Italian lira (of course the plural for lira is lire, which sounds about the same.) I've also not heard anyone say bahts. There are other words in the English language where the singular and plural use the same words, such as moose, sheep, and deer, so there's really no reason to create a new plural word if the singular form is already acting as the plural.
Solution 2:
I have only ever heard/seen "100 baht", not "100 bahts". I've never dealt with ringgit.