I updated the SubstitutionFilter.java class in order to allow regexp on the subst filters by using the operator "~>" to state the first argument is a regexp. The default behavior is maintained if no operator (i.e. remove string) or "=>" is used
This is convenient for mass corrections or in case we'll have some tweaks to apply on street address names to facilitate search, for example the style entry below (Carlos!)
highway=* & name ~ '[Aa]venida [Dd]e [Ee]l .*' { add streettype:movend='${name|subst:Avenida De El |subst:Avenida De el |subst:Avenida de El |subst:Avenida de el |subst:avenida De El |subst:avenida De el |subst:avenida de El |subst:avenida de el }'}
will become
highway=* & name ~ '[Aa]venida [Dd]e [Ee]l .*' { add streettype:movedend='${name|subst:[Aa]venida [Dd]e [Ee]l ~>}'}
Technically, the change is minimal, it is just checking the filter operator (=> or ~>) and using replaceAll() instead of replace() if "~>" is used.
Attached the updated class - I really hope it will be included and be useful!