i search up the keyword but nothing shows up, empty..It might surely be only a question of activated or non activated filters in the server list.
That's mostly the reason why a server cannot be seen.
At the left of the search in AC Launcher, there are 7 filters possible .... from left to right, you'd better have those 7 filters as this: 1st greyed - 2,3 and 4 red - 5,6 and 7 greyed.
Now ... in the search itself, surely rather search for the most specific word for this server. So if the real server name is a bit different, you'll find it anyway.
NB: grey is "unactivated" ... red is "activated"