If you’re certain tren caused this (I would strongly suggest looking at all lifestyle and autoimmune factors) then why in the world in this moment would you even be considering “how much tren can I run in the future?”
I respect everyone’s choices, but unless you’re going for a pro card or this is your job… is it really worth the tren? I will never forget what John Meadow’s said- “I thought I had to use tren to compete until I realized I didn’t.”
The kidneys are slow to repair themselves IF they do once damaged so I would of course remain optimistic, but know that maintaining and restoring kidney health after an event usually becomes a new lifestyle, not a one time fix.
Either way, speedy recovery and remember bodybuilding is a long term play. I used to love tren (ok and still do lol), but I love my health and being able to body build more.
I’d get past this, healed and then make those decisions if it were me.