I am looking for a tournament software for Ubuntu/GNU Linux. Badminton. Enter players, system. Not using anything at the moment, but looking for something. Sport Software link
Through wine I managed to install and run: Tournament Planner
Something might exist but this strikes me a as pretty niche market.
Small markets mean there's a much lower chance of there being decent software to cater for it. Any development that does happen tends to happen online where developers can ensure they get some sort of kick-back.
If you can't find a desktop app, you might want to try turning to the web. There are a few websites that claim to help solve problems like organising community teams and events, though you may have to do tournaments manually in Inkscape.
Annoyingly I've also lost a link to another site like the sportmeets site that did look interesting... But you get the idea. There are sites out there that come close to doing what you're after.