> I should specify - it's hard in that it's troublesome to have to code switch and do a bunch of recall before working on the thing.
You don't sound like you have any experience working on software projects. I can tell you it's not hard to switch between programming languages. If anything, the difficulty level is placed on onboarding onto projects you are not familiar with, but the programming language in use is far from being a relevant factor if you already are familiar with it.
you're completely missing the point.
Even if it's 'not hard' your brain has to compensate for switching to another realm/space and that takes energy and time especially if you haven't used that particular space for a long time.
This is backed by science. Go read up on short-term working memory and crystallized memory.
All this will add up the maintenance costs, so it had better be a good trade off.