I’ve been told by David that G’MIC 2.4 will allow for completely localised versions. That’s good but not good enough in the long term. IMHO, the sheer number of settings for most filters requires tooltips with a short description of what each option does/changes in language understandable by mere mortals who aren’t developers.
On a technical level this can be done easily in Qt, but I know that it would divert developer time away from coding. However, G’MIC is such a powerful tool that it would be a shame if it couldn’t be used by more people, simply because there is a scarcity of information on how to use it properly.