Fir Audio E12 considered a flagship model for electron series?
Yes, it is.
E12 is generally considered the more "audiophile" tuning.
E10 is generally considered to be more for "artists, mixers, and sound engineers" tuning.
Basically, one is more energetic, fun with stronger bass and impact. The other is more neutral and reference.
They are both excellent - more of a taste/preference kind of choice here.
Guys what's the full form of FiR audio (even if redundant)?
Here is from the top of my head:
Current Models - Frontier Series
Neon 4
Krypton 5
Xenon 6
Radon 6
Current Models - Electron Series
E12
E10
Sister Brand - Bellos Audio (for performers and audiophiles who still want a custom like experience on a budget)
x2
x3
x4
Retired Models - M Series
M2
M3
M4
M5
Retired Models - Solos & One Offs
VxV - replaced by Electron series
@bogdan belonozhko can confirm, but this is pretty much everything I believe that I can talk about / made it to release.