I wrote "we are en route". Should this also be accepted as standard English even though it is technically French!
Is: 'We are travelling!' not correct?
You need to translate the sentence as closely as possible. 'We are travelling!' is better translated as Cestujeme!
"We are on the path" is also possible?
In the meaning: We are standing on a footpath. We found the footpath. ? Perhaps it might be added... But it certainly does not mean the same as We are on our way.
I will add "on a path" now.
Proč nejde journey?
"We are on a trip" was accepted, but ... I feel like that is completely different from "We are on the way!" Can it be used as both, or is "on a trip" a less likely meaning?
It's a much less likely meaning, but it's possible. The most common way to say "we are on a trip" is "jsme na výletě".