Well I am the main coder for minnowbooster ;) We may have a team that helps with many things but the code is still mostly done by me.
If you need advice on how to detect many problems with steem, I may be able to help you implement them. Many are really easy to fix once you know it.
Most of these errors got fixed by a user complaining, me checking on what happened and what a clue was, that something is wrong, then just sending the money back once I notice that clue.
I fixed problems in similar manner.
The biggest difference is the time I am willing to spend on fixing problems.
I am a lot less invested in Steem, after all.
As for difficulties - so far I haven't had any.