While I haven't seen anyone check the SFI sticker on the helmet condom (I'm a d`ckhead), IIRC the rulebook states SFI which means sticker should be there.
Now here's the rub, not all "SFI approved" items can keep a permanent sticker attached reliably. Condoms, arm straps, padding, etc, can actually have their SFI tax paid, yet not have the sticker on it.
To play it safe, you should have the sticker, but in a pinch I'd print out the sales literature from the internet on the item indicating it's SFI, but the sticker is no longer present.
I did return a "true SFI" head condom made by a major MFR (RJS?) that didn't have the sticker, and when you buy, you should always do that. Luckily they are cheap.