I use LanguageTool 3.2 embedded in OmegaT development version.
Whenever I enter a “double” punctuation sign, I have the warning “Point d’interrogation (or whatever sign it is) est précédé d’une espace fine insécable” (Question mark should have a leading small non-breaking space) even if I actually use a non-breaking space.
Previously, OmegaT used LanguageTool 2.2 and it works fine.
If I try the online test page I have the same false positive, so it seems unlikely the error comes from OmegaT embedding.
I thought perhaps the rule had become more strict, really requiring a small (“fine”) non-breaking space, but that doesn’t seem the case according to the source code:
// Strictly speaking, the character before ?!;: should be an
// “espace fine insécable” (U+202f). In practise, an
// “espace insécable” (U+00a0) is also often used. Let’s accept both.