Thanks for your answer Rinigus.

Then the French translation of "Map matching" is inaccurate. Actually it is broken anyway: it reads "Fuse la position sur la route" but "Fuse" does not mean anything in French. If I understand correctly what this option does, it could perhaps read "Forcer le positionnement sur les routes" or something similar.

Good to know that Follow Me and Navigation modes force Map Matching regardless of what the user set in the settings. It might not be trivial, as shown by the fact that I thought having Map Matching unchecked was the reason because I had no speed limits displayed.

I created an issue on Github.

You mentioned that Stadia does not provide speed limit information, and therefore this feature is only for offline data "for now". Does it mean you have ideas to expand it to online data later, or that it is fully dependent on whether Stadia adds this as a service in the future (I guess it is unlikely)?