As business owner I fully understand your approach to create another subscription revenue stream with the Universally language translation plugin.
But as a customer I would prefer an open API to my preferred AI providers for to do my language translations like the colleagues at discourse provide, where I could decide the provider and the model I want to use, where I could adjust the quality of the translations, I also would prefer to host the translations on my site and not remote and risk to loose the translations where I already paid for when I cancel the service..
Please check how discourse solves this and consider such a solution for your premium subscribers.