Don't know the exact diagnosis, but I've had the occasional, temporary, random pimple-like spots over the years. Whatever they've been, they were practically always no big deal. Didn't seem contagious, occasionally a couple of fish would get them, but not something that spread in the tank.
Was a mod on a now defunct frontosa forum for years, people would get them from time to time, every so often someone would post and ask about them. Typically the same thing-- occasional, random and not serious. Won't guarantee yours are the same, but typically looked like your photos. Always recommended the same thing-- clean water, little salt and/or a little Melafix-- which usually took care of it. Clean water alone also worked, just a bit slower.
When I say a little Melafix-- Melafix is known for causing fast breathing, I've seen different theories as to why. I tinkered with it and found using less than the label recommended dose works just fine for most minor scuffs, the occasional minor pimple-like spot, etc., with less of the fast breathing effect (which is temporary and seems harmless enough). For me that means 1/4-1/3 dose in many cases.
Probably yours are the same thing-- unless they multiply, which would be something different.