Makes sense for forums that want most things translated. I want to float the inverse case as an RFC and gauge how common it actually is:
I’d like to translate only one busy multilingual category (e.g. “International”) and leave the rest of the forum alone. With exclude-only that means listing every other category, and every new category I add later gets translated by default until I remember to exclude it 
an easy way to pay for translations I never wanted. An opt-in ai_translation_target_categories (include wins if set, else translate-all-minus-excludes) would fit this cleanly and is safer for cost control.
How common is this scenario for others? Do you want translation forum-wide, or scoped to a single international/off-topic category? Trying to gauge whether an allow-list is worth bringing back or if my setup is the niche one 
.. 