at some point you end up with path dependence -- you're in the situation you're in, and it would be big-bang rewrite or incremental migration to port all the code to a new stack, not to mention the costs of retraining existing staff to be able to effectively develop in and support the new stack, or replacing the staff with different staff who know the new stack but don't understand the existing business and code. so maybe the previous decision to pick tech stack A over tech stack B when starting the product was pretty sound given the circumstances, or maybe it wasn't, but it doesn't matter that much from the perspective of deciding what to do next.

Oh yeah, I know all too well about path dependence. That's how we end up with a Rails monolith that's written in a very standard/structured way so that many devs can contribute, add type annotations for safely/docs, etc. Using no types is like having no tests and thinking about adding them later. Usually better to have it in place as you go.