to rephrase: i believe it is not against happyele's ToS to commission art of their characters. it is against the ToS to be commissioned art of happyele's characters!

it's typically a responsibility that lies on the one profiting from the exchange. profiting off of the ensemble stars franchise is against the ToS, and this is typically the case for nearly any franchise out there, otherwise they will not have much power over their franchise's merchandise.

that being said, if you're familiar with things like artist conventions, you probably know this is a very grey area, as most franchises do not target artists, as long as they do not infringe on the type of work they are putting out (i.e merch using official images) or use their franchise to advertise their for-profit business. in japan, it is also very common to sell only original work and instead give out fandom-related merchandise as freebies as a sort of respectable loophole!

anyways, similar reason to why i translate, for free; i do not claim to be enstars' official translations and i focus works that aren't in the english versions.

anyhow, they have it stated in their contents guidelines: https://www.happyelements.co.jp/contents-guideline/