Possible Options:
- .NET Reflector
- JustDecompile (FREE)
- dotPeek (FREE)
- GitHub - dnSpy/dnSpy: .NET debugger and assembly editor (Jose says best thing since sliced bread)
Also its quite possible that certain template you are using incorrectly. Even if you decompile, you can only look at the logic, I wouldnt attempt to modify it since most of it is obfuscated. We are currently implementing Epicor and have been for 5+ years at 20+ locations and part of a Cut-Over is to DMT in data from AS/400 IBM Systems, Microsoft Dynamics etc… into Epicor; we haven’t really found any show-stoppers.
But Epicor comes with a RESTful API nowadays, you can fix it writing some REST Client or even using Updatable Dashboards and I think Excel even lets you connect to a Data Source.
You can also report your bug, issue here on the forum - see what the community makes of it. Epicor is watching this forum, even one of the DMT Creators Mr. Edginton @Edge is part of this forum (former DotNetIT) and today VP of Development at Epicor.