Is there a way we could actually know this?
It's impossible to know for sure, but it definitely looks like they are severely insolvent. I have seen how even non crypto services acted similarly, and it all ended bad, unfortunately.
And how is that even possible when every time you send coins you have the coins, I just don't get it.
It's not every time. People have complained a lot about their deposits were not posting for half a day, or even days straight.
I haven't had a problem just yet but it does worry me as Cryptopia was amongst my favorite exchanges.
It should worry you. While you still don't experience any problems, which is quite an achievement on its own, withdraw your funds as soon as possible. It's just not worth it to keep your funds in an exchange that might turn you into a victim as well, and with everything that's going on in mind, it doesn't even make sense to keep using that exchange.