I totally agree; while it makes sense for TakaraTOMY's Japanese market where the FIRRIB mix up never happened, it doesn't make sense for Hasbro's Anglophone market where indeed the purple robot was Rumble. Frenzy was NEVER purple in any original G1 medium. (cos blue =/= purple)
It really feels like Hasbro got lazy/inattentive with this important detail and missed a golden opportunity to finally have a cartoon-like Rumble and Frenzy toy set with the correct names.
Soundwave's eyes were yellow in ALL G1 media except the cartoon. They were yellow in the toy, US Marvel Comics, UK Marvel Comics, Ladybird story books, Big Looker story books etc etc etc. The cartoon was the sole G1 medium in the 1980s that gave Soundwave a red visor, so in actuality Soundwave had a red visor and it was FIRRIB in the G1 cartoon and nowhere else. Everywhere else saw Soundwave with a yellow visor and RIRFIB. That's why I prefer original toy accurate colours, because the toys came first, and the majority of G1 canonical sources stuck with the toy colours. The cartoon was exceptionally unusual in deviating away from the toy colours in certain regards. This is also why I personally refuse to use the term "show accuracy" or "cartoon accuracy" with most Transformers toys, especially G1, because the term implies that the cartoon was more correct than other media, whereas in reality it was the other way around. (JMHO)
So I really like how Hasbro's gone and given their MP Soundwave a truly G1 accurate yellow visor; the way Soundwave's visor is meant to be. I would've personally liked to see Frenzy repainted blue like the G1 toy (instead of being left purple) and keep Rumble as Rumble, thus making the entire set really G1 accurate. But if they are going to keep Frenzy purple as they clearly have, then I completely agree that it would've made a helluva lot more sense to call the purple robot Rumble and the red robot Frenzy.
It's the exact same gun! Hurry up and open your 20th Anniv. OP!