I think the button “bell” sound would integrate in the game better if it were more like a cowbell. Thus, it could be bit clangier but also it should naturally damp quickly rather than ring as the current bell does.
The idea of a “neutral” click is also a reasonable alternative. But of course it is more fun if everything is thematic.
If you like, check out the bell utility I have online:
http://hexara.com/SpiderBellDashboard.htm
Be sure and put in the following settings:
Tone - I’m thinking about 3/5ths or 2/3rds sounds best for a “cowbell”
Note Length - use the minimum! (it is maybe possible for me to even fine tune something to be shorter still)
Octaves - might as well just set it to the max (7) but test out notes near the center top. (Loudest & middle pitch range.) It is possible to pick pitches that fit or contrast the music.
Feel free to record any of these and make it into a cue.
Also, these sounds are generated live by Java, and we could probably customize a little library or jar to add to your program. But if you use just one or two of them, there would be little reason to trouble with the live code, as the resources would be relatively small for audio, the cue being so short. (I estimate the needed code at about 100KB, in comparison, maybe more, to integrate with your other sound cues.)
By the way, I really enjoy the game and think you have done a great job.