securing the Montefortino A-question

[Peroni]

But the question remains: could this type of strap be retrofitted onto other helmets, not just Montefortino and Gallic A? Seems too good not to continue. Am I missing something as usual?

We generally see this type of fastening on older style helmets. The Montefortino types especially. The Coolus C types from Schaan have the same system as do a few similar shaped cheekpieces in other collections. (One of which has a series of rivets for what appears to be for attachment of a liner)
And then of course the Gallic A (Augustan period) After this we see the introduction of the tie-ring system. On some Italic type cheek pieces we see a double ring-tie system. (Italic E)