When we upgraded the tool, we expected the tool to have issues with major versions of ArcGIS (e.g., 10 to 11, or 10 to Pro), but had not anticipated the degree to which code results would change with minor version changes (we even had code issues going from 10.3 to 10.3.1 !).
To my knowledge, there is also not the equivalent to Travis-CI for ArcGIS, where one can run test code against multiple versions of the software at once. I have even struggled to have more than one version run on a computer at once.
Also, to my knowledge, no one is actively funded to maintain the project.
Sorry for the inconvenience,
Best,
Sasha