2 Propane pressure reducers??
So question?? If you hook your stove directly to a propane tank does it take less time to, say, bring water to a boil??
The propane appliance quick connect hookup at the side of your trailer is low pressure already . . . Where the RV propane tanks are mounted and you connect the pig-tail there you have a propane pressure regulator also there (Propane at 11" water)
A coleman propane stove has a pressure regulator built into the silver tube (also 11" propane supply) you connect to the side of the stove. This type of stove will not run from the appliance hookup quick connect. If you try there are now two pressure reducers in the total propane supply and not enough propane gets past both reducers to where the gas burns. Could this be the slow heating that you are describing??
Are photos of your setup with all stoves available to share here??
2012 Rockwood A122,
2017 Kia Sorento 3.3 V6 AWD ,
2012 Subaru Forester with MT (gone to TV heaven)
Cheers and greetings
from a Toronto Canuck