I finished 15 more rooms. Technically 14, since one of them is an easy variation of another. I focused on making harder ones, so I could use some feedback on whether they're too difficult for the average player. I'll submit them to Mantis once I'm done updating them.
Edit: Updated to 1.1, which will likely be the final version.
Usage instructions: extract the .zip file in the Skyward Rogue folder, and combine the folders. The levels will now appear randomly in the game.
You can also try them out individually. Open Starward Rogue\RuntimeData\Configuration\TestChambers\a_testReathRooms2.xml in a text editor. Start the game, then pick the mods options in the file selection window. Select a_TestReathRooms2 in the Test Chamber dropdown. The first level will now load. To change levels, alt tab to the text editor, then copy and paste one of the room_setup scripts on top of the one at the top. Return to the game, press esc and select reload test chamber. The new room will then load.
To remove the new rooms, delete all the files that were added with the zip in the Starward Rogue\RuntimeData\Rooms directories.