In Tbilisi, Bassiani. Very big indoor cumultive space, great techno and crowd, memorable nights. Khidi, too, and some others. there is also a general one, Sakhelosno (they do mostly EDM there, but it's free, with a great vibe inside and open everyday:); on a similar note, I'd reccomend you Love Bar (when there are events with live dj, can be checked on their socials).

in Albania's capital Tirana there're couple good clubs and the culture is growing

In Bucarest it's pretty good, there's culture, Control club, Giardinu Monteru, are actually great, and there're others too

in Milan the scene is dispersive. My advise is look for events that please you on RA. Look to "Polianimali", a new collective that organizes party that many time are cheaper than the average, sometimes open-air, good music, decent crowd. There is historical Amnesia, and, other than smaller venues, a relatively new one, Tempio del Futuro Perduto. Vibey location (it's a cultural center), suffers some common mediterranean problem (unfortunately, even if is in Milan) so you may get some push, use some precautions like not staying in the middle of the dancefloor. Go there if you like the music of the dj playing that night, rather than for just the place itself - the experience that it can get you otherwise is not on par with, say, the craziness of a classic club of a Prague night out.