Not sure if this is "as designed" or a bug.
I have a set of actions for fixing (changing all letters to uppercase) roman numerals in track names and they use the Replace action and select "only as whole word" option.
The seem to work correctly except in the case where the roman number is immediately followed with a period character, in that case the string is not replaced.
Example Actions: (all with 'only as whole word' ticked)
Replace "ii" -> "II"
Replace "iii" -> "III"
Replace "iv" -> "IV"
Foo Part Ii -> Foo Part II
Foo Part Ii. -> Foo Part Ii.