If you suspect a lesion is infected I would strongly recommend against using super glue on it. The main ingredient in the glue available OTC is cyanoacrylate which breaks down into cyanoacetate and formaldehyde, both of which are toxic and can lead to nasty inflammatory reactions (plus the glue REEKS!
). I've heard that vets sometimes use a super glue called Vetbond which has longer alkyl chains, but I'm not sure how and when they would use it.
I think if you keep the lesion clean and dry and it shows no improvement (or worsens!) that you should take Herman to see a vet. It might not actually be infected, but it certainly won't hurt to treat it as if it is! Its always better to err on the side of caution, after all.
I've actually used marine epoxy (I first applied a membrane to an area that came in contact with the flesh) to repair damage a female apple snail of mine sustained during a fall onto the floor while attempting to lay eggs. Shes had the epoxy on now for the better part of 6 months and is still rocking around the tank just fine! I've entertained the idea of attaching the empty shells of other snails to her just to make her look badass! ha ha