Hi, welcome to the community.
The version rule you have created is based on the
file name (topmost field in the dialog).
This rule finds versions by looking at the file name of the master (cr2 and cr3 files, in your case) and then searches for versions matching the file name of the master, applying the regular expression in the field
link expression.
The time tolerance field is available for version rules which use the EXIF timestamp or GPS timestamp to find versions based on date and time.
See
Link Via in the IMatch help for more information.
Maybye
Auto-Stacking is what would work better for you?