The current Revit functionality does not respect the line thickness in the pattern and does not allow to change the thickness.
A needed feature would be the ability to change the line thickness of the pattern to allow for free customization. This option would be helpful when using brick patterns, which would allow you to change the thickness of the grout.
With these tools available, many modified patterns based on the PAT file could be created directly from Revit, without the need to modify the PAT file.