Why did you not show how to install the case drain hose onto the case drain filter housing? Like removing the deck plates and installing the required Tee fitting on the filter housing so you can install the case drain hose you are showing in frame 2.33 and forward.???
The work you did with that mini attachment, can be done with a trimmer and a chain saw with out leaving any stumps and to finish it up a rake to clean up the mess ang plastic garbage bags huge ones and a trash can that can hold up the plastic bags.
Try changing control patern to Deer. If it's having a hard time booming up in Cat, switching it over to Deer should move the mower circuit off of the valve body that deals with main boom cylinder. It may move around a bit better for you when mower is on. Idk, worth a quick try.
After using it more in heavy brush, it does ok running the mower. But my model is the the e35i (25) hp. I believe these have around 16 Gmp hydraulic flow.
What you just trimmed can be done with a handheld trimmer and a chainsaw and without leaving any stumps and to finished it up you need a rake a trash can a big one and plastic bags ( big ones) to clean up. i did it without a $10,000 gadget