Actually, you're supporting Kagura not Inusuku by buying the Steam release. If you want to support Inusuku, buy the original DLSite version and use the fan translation. If you want to support more Inusuku titles being brought to Steam, buy the Steam release.
With recent news that credit card companies technically blocked all visa and mastercard payment on DLSite there is no easy way for non Japanese to support Inusuku.
I may dislike Kagura games as much everyone here , but lets be real - right now Kagura steam release sold more than DLSite in very short time.
Inusuku will get a decent profit even if Kagura takes their %.
So if everyone will boycott Kagura , that means only one thing.
Credit card companies blocked DLSite + No steam sales = Inusuku will not get money and will give up on official EN version.
I may be a shameless pirate , but if poor game developer can earn money so he can make more good games i will not care if it is Kagura games or another porn game company.