The main problem with products like that is that they affect all the rubber parts in the trans and not just the leaking seal.
Then when the effects of that stuff stops working all the rubber that got softened by it hardens up faster than it would have.
Then there is also the part where it could be a crack in the converter pump drive snout or the weld around it and the trans life gets shortened by the additive for no reason and you still have a leak.
Not saying don't try it, just an FYI in case you didn't know the risks.
