I find that when I use FMGo, some recent data is lost if the database crashes.  Is there a way to 'flush to disk' on IOS to prevent this from happening?

Redesign it and use the transaction model proposed by todd geist and others.

I've tried to find info about your suggestion, but have come up empty.  Looks like a lot of work.

 

Any simple solutions, like 'flush to disk'?

https://www.geistinteractive.com/filemaker-transactions/ - and it is some work... all depends on how much the integrity of your data is worth...

You can use Commit Record to commit the current record, which for a simple system may be enough to reduce this issue.