French sorting

It can, as long as it follows the default sorting. Currently, all templates that generate sort keys for French use format_categories in Module:utilities. In the end, they should all use that, but it's a gradual process. If you find any that don't use it, let me know.

If you want to check, you can add a sort key and see if the entry ends up in Category:Sort key tracking/redundant or Category:Sort key tracking/needed (both are hidden). If it doesn't, then the template doesn't use format_categories yet (or perhaps it does, but isn't giving it the sort key for some reason). But if it does, then you can see whether the sort key is redundant depending on which of the two categories it ends up in.

This reminds me, {{mutation of}} isn't sorting (last I checked) and often seems not to be even fed with sort keys. Not sure how to fix that one, though.

I fixed it. {{deftempboiler}} supports sort keys, but {{mutation of}} didn't pass the key on to it.