What Josef posted is not an incorrect path, it is the correct path with the algorithm of how G41/G42 has to work, it is not a bug of Mach3.
Then maybe the algorithm is flawed? I'd like to see the code that produces that error.
Can't you check the comp when the g-code is loaded, looking as far ahead as you need to? If it takes time, give the user the option to enable or disable check for errors when loading.
Sorry, but I've been using comp for 20 years and have not seen the issues that you are bringing up.