I was going to mention Schaff. I have a copy of his Creeds in my office, a legacy from my wife’s grandfather, a pastor. I have always meant to copy some of the creeds over into my Greek Bible.
Caspari, I think, is Carl Paul Caspari’s “Ungedruckte, unbeachtete und wenig beachtete Quellen zur Geschichte des Taufsymbols und der Glaubensregel”. I see volumes 1 and 2 on archive.org, but I can’t get to Hathi right now, which I would suspect has v3.
in later Greek, ἄν with relative words is used with INDICATIVE in all tenses, as ὅπου ἂν εἰσεπορεύετο Ev.Marc. 6.56; ὅσʼ ἂν πάσχετε PFay. 136 (iv A. D.); ἔνθʼ ἂν πέφυκεν ἡ ὁλότης εἶναι Phlp. in Ph. 436.19; cf. ἐάν, ὅταν.