Did not have time to actually fix them now, but managed to track down the error.
The tests that fail are related to this change in Checkstyle 5.3 (all tests run fine with 5.2)
As far as I can find out, cacheFile is specified in both min-plugin-config.xml and in sun_checks.xml (with substitution property), and this creates problems due to the previous mentioned change, where the absolute path would be added to the property with a comma to separate them. This obviously fails when trying to create the file...
So the bottom line is that so long that you do not specify e.g. cacheFile several times in your config, you should be all clear.
I am not sure whether this is in fact a bug with 5.3, or if it is a result of maven-checkstyle-plugin using the Checkstyle API in the wrong way.