I must admit i'm not sure if all spaces are needed, but for sure some are.
You can look at screenshots in the french discussion i pointed to better understand: the problems are not double spaces (ignored by HTML rendering) but missing spaces.
Choice has been made to integrate them in strings rather than in Moodle code, and i wonder if it's the right way of doing it, and if there are recommandations about that.
In fact, when looking at translations, some (rare) have beginning space, and most not. If you launch, from moodledata/lang folder the command grep criteria_descr_bydate */badges.php | grep "'] = ' " you'll see that de and hr languages have beginning space, but most languages not.
I just don't know if AMOS doesn't allow beginning space, or if it just don't see the difference beetween previous existing string without space and the new one with space. If it's the case, perhaps it could be possible that the language maintener modify the string, and validate it, to be able to modify it again, adding space.
Even if it's possible that way, i still wonder if it shouldn't better be directly encoded.
Séverin