Travelling 1600km by bus is… urgh, a bit painful. Even if you get a nice bus, where you can comfortably sleep, with plenty stops, lacking annoying loud people, you’ll probably feel glad once you hop off. Doubly true when returning home.
If you’re still doing it: a book, a fully charged phone and/or laptop (remember earplugs!), comfy clothes makes it more bearable. Don’t assume the person next seat wants to chitchat, or can chitchat about interesting topics.
It’s a good idea to have a water bottle and something to snack on, even if you can stop midway to buy food. My go-to snack was nutrient bars - they take almost no space, they’re discreet¹ and filling enough.
so I assume young people and public facing employees at the bus exchanges to speak some of it…
Don’t assume; look for that info. Preferably on a city level if possible/available, but if you can’t find it at least on country level.
Also take in mind that plenty people don’t feel morally obligated to shift languages based on outsiders’ convenience, even if they do speak it².
A big “fuck you” to the muppet on a 600km bus travel that I did, who decided to eat pork rinds while in the bus. That “CRUNCH CRUNCH CRUNCH” was aggravating.
I’ve seen this two times. In two different countries. I’ve seen the opposite too, people going the extra length to help you out, so don’t take it as a general rule, just keep it in mind.