Same! I'm applying to Albania for a research grant and currently don't know any Albanian.
I think it's kind of a personal judgment. Learning a language is always a plus, but, like you, as a full-time working adult, I don't have the time, energy, or money to commit to something I that I may or may not ever use. Depending on when the Czech ETA program starts, you may have enough time to get a basic understanding under your belt if you commit for a couple of months (that's my plan, anyway. The Albanian program doesn't start until October). I think if you can start learning a little now, excellent. If not, I wouldn't worry about it.