https://ngosang.github.io/trackerslist/

I don't have direct answer to the question, but I generally don't add public trackers to my (public) torrents. DHT/PEX usually works fine for me for finding seeds on the occasion that I do need something from public torrent sites.

I wonder whether adding additional trackers only increases the speed in which peers are found or whether it also substantially increases the likelihood of finding peers.

Whatever shows up here: https://newtrackon.com/list

Only lists trackers submitted that are online with a 95% uptime.

honestly... I don't know what a tracker is, I just click the magnet button and qBitTorrent just downloads it
Is there something more I should be doing?

That's a waste of time. The torrent already comes included with the needed trackers.

What is the point of adding other public tracker? Is it to cross seed? Or just higher probability to connect to a peer?

Doot for later

I add a bunch I copypasted from a list somewhere