It’s indeed this search which I was asking about.
It was mainly due to the fact that previously, our forum used the Multi-lingual plugin, which is no longer supported as of writing, which allowed to filter topics by languages, and search either languages since our topics were written twice, in two languages (french and german), offering an equivalant experience for both languages - as such, searching directly the translated content would have been beneficial for us to replicate the experience.
However, since you meet issues with the search as it is currently, I understand how it might not be high on the features list.
The ability to localize specific topics in several languages is already a big plus and a welcomed addition !
As an additionnal question, have you got any plans to search/filter topics by topic language ?