I am not too familiar with this topic and would like to ask you some help. Are some servers known to broadcast certain tournaments?

I can just help by adding a list of servers I know: wbaduk, igs, wins, lgs, cyberoro, tygem, eweigi, tom, kgs, ogs..

Without doing any work, I can just say that IGS shows the Pandanet Go European Team Championship, but they actually play it there anyway, and that is not a pro tournament.

Thanks

Wbaduk broadcasts loads of Asian pro tournaments. Several games per day. The Japan server tends to keep them around for longer, just checking now there are 34 recent pro (and ama from the euro pro qualification) games up.
IGS broadcasts quite a few Japanese pro tournaments.
KGS broadcasts amateur tournaments in Europe and America.
cyberoro ~= wbaduk.
tygem and tom similarly have asian pro broadcasts I think but I don't use them.

Alright, nice. I log into tygem sometimes, and I can see the live relays on top of the list by default, but I have never seen any of them being actively played. There are no observers in those relays either. I guess I am always logging in too late.

How about some of the bigger and more known tournaments. E.g. Is Jubango relayed somewhere? The japanese 幽玄の間 app is relaying some japanese pro tournaments for example the honinbou match tomorrow, but the app has a fee. ( http://u-gen.nihonkiin.or.jp/ )

The Gu Li Lee Sedol Jubango is on IGS and Wbaduk at least. Past games had English commentary on KGS from Myungwan Kim 9p but I don't see a notice about that for game 5.

幽玄の間 is wbaduk. The English version is free.