You're much better off hiring people who are capable of learning, and then giving them the opportunities to learn and advance their knowledge and skills.
You're better off hiring experienced people who are highly productive. If they're highly productive with one stack, it makes no sense to change their stack so they're no longer productive, or hiring people who aren't familiar with it and waiting for them to become productive.
There's nothing wrong with using old, well established things. They're quite often better than new things. As long as they're still supported, just use whatever builds a working product. It's the end product that matters.
The difference between Japanese and English is much, much bigger than the difference between one Unix OS and one Unix-like OS. This is a remarkably disingenuous argument. If you really don't understand the difference in scope, there's no point in discussing anything with you because you've managed to disprove your opening sentence with yourself as the counterexample.
(Japanese isn't so radically different from English, it mostly just has more words for more contexts. In many ways it's simpler than English. It would be harder to go from Java to Haskell, with their many different language paradigms)