Brokepilot... What regs would those be... FAR's ? Yes in USA English is the only official aviation communication language for ATC purposes.
ICAO allows local language to be used for communications. So 2 aircraft talking to each other in their own language is not against the regs, but on a frequency that is meant for other purposes than socializing, shows bad judgement.
When flying over the Atlantic I often hear Airline from my home country making pos reports on HF or using 123.45 for some function. When I talk to them I ask them to switch to a frequency that is not used in the area.
Do I think that English should be the only language allowed for aviation... Absolutely when there are pilots around that do not speak the national language. That is almost all the time and all over the world.