Show an additional summary page before being able to submit
Rename the submit button to "create note in OSM" or maybe better textually add that "a note will be created and it is up to the community how fast this will be reflected in the map". So that people will not wonder why / when their business will be visible on the map
Add a "thank you for creating ..." banner / page / hint after submitting, so that you know it worked
I like the final summery/ conformation page. It's a good way to catch typing errors and hopefully will reduce duplicate posts (maybe??).
2a. I'm not sure we can make it clearer that you are basically creating a change request that will be handled by a volunteer. Beyond the "dot org" and language that is already present, people can't expect a volunteer non-profit group to jump into action just to make sure they are on map within a certain time-frame. If it is that important to them, they can have a SEO or another advertising profession to add their business immediately.
2b. There is also a lot of language translation overhead involved even with small changes to button and other messages.
Think we have a "thank you" message but have no problem adding one if we don't.
Some ideas