...After the can light the remaining hose is still long either in the chest area or forms a big bow around the neck.
Interesting about the hose bowing out at the chest or neck. Usually you only see that with the bungied backup if it's too long for the diver, rather than the long hose. The typical 22" short hose is usually too long for a petite diver (like me as well), who might need 20 or 18". Are their backup hoses bowing out and affecting the placement of their long hose? Yoke regs stick out more and affect the placement as well. Are the hoses routed in the most streamlined manner?
Are their tanks set high on their back so the first stage is behind their neck or head? That can cause the bowing out.
They would need to lower their tanks so they're not protruding high up, but they can still reach the valve(s). This will allow the hoses to route in a streamlined way, not bowing out.
The excess hose just gets pulled down and back past the right hip. That's perfectly acceptable and common for a single tank diver, especially without a drysuit.
Managing a long hose is of course a skill in itself, in the placement, routing, when kitting, and in the water.
Pictures of them wearing their gear would help to see what's going on. Good luck!