Ah, my mistake, I saw "fluted" and read pushers, sorry. Missing fluted pushers isn't so much of an issue, as they are readily changed and somewhat available.

Registers that aren't ridged however, can be more of a problem - this is often a sign of a refinished dial as the rediallers find it easier to paint on the flat surface than over the ridges. There are some exceptions, like Arno's tropical Carrera prototype:

Have you been able to check the watch in the metal to see if the ridges are actually absent? They are quite fine and tend not to be as obvious in photos on the black registers as they are on the white. And finally, any Siffert expert able to confirm that they should always be ridged? I'd expect to see them myself, but mine is more a passing interest in Autavias so it would be good to get word from an owner or two.