Actually, the way this is supposed to work (now Beta 2) is that if the program sees a param file that was open in the product params library, at startup it will try to substitute the current level params library seamlessly. This was to cope with the very type of error here where an error would be fixed with the latest version. The problem here, though, is that the kato-N.xtp file at v5.1.2a has been renamed to N-Kato.xtp at some point for v5.2.0 Beta2. So that logic won't work to get past this as intended.
I'll let the team decide if we need a conversion table or logic of some sort to find the right file, or if that rename is causing more harm than good - especially now we have Martin's lookup code to find param files by their Content field.
The CheckPaths() code was added and is performing more checks than it used to - to try ensure that all track segments are in at least one path. That is the warning error here. I'd have to guess that problem was fixed for N-Kato...
The terminating error is most likely something else in that old file that is not in accordance with the latest level. Did you get an actual error message before shutdown?