PLURAL and GENDER optimization

Functionally, they are identical, of course.

The question is what is more useful for translators and reviewers, both in terms of content and in terms of the review process.

In terms of content, you should decide how to write things, and document this decision with an explanation. I'll give you an example from Hebrew, the main language into which I translate. The Localisation guidelines explicitly recommend writing whole words inside the GENDER clause and not just the suffixes. (As I was writing this reply, I was surprised to discover that it was documented only for GENDER, even though the same practice has been used for PLURAL. I've just added it for PLURAL.) The explanation for Hebrew is that using whole written words is better for finding them using the search engine.

My French is not perfect, but as far as I can see, you don't have an explicit recommendation for that in Localisation guidelines/fr. I recommend writing it explicitly. I am not telling you what the recommendation should be—you, the translators into French, should discuss it and decide it. You may use the same logic as in Hebrew—that it's easier to find words using search engines. Or you can decide that the opposite is more comfortable for you, for example because you want to reduce repeated words. It's up to you, but you should document it and try to be consistent. (Also, it is not documented, but in Hebrew, repeating GENDER and PLURAL many times just for the sake of not repeating strings adds too much syntax and mixing of different writing systems, and it makes translation unnecessary complex, but it may be less bad for French. Again, up to you.)

In terms of updating and reviewing process, the people who complain that too many updates just for the sake of consistency are not great have a point. Consistency is good, but this should be at least discussed because a lot of edits make review difficult. And if the practices are documented, enforcing consistency is more acceptable to everyone.

Now the tricky part is to agree about what to document ;)