Honesty I don’t think it’s really leaking very much and I would probably just keep an eye on it to see if you think it needs to be fixed or not. I’m fairly tolerant of leaks that are slow and not making a big mess.
Do you have a fill port or vent under and in front of the seat? See below for diagram. If so you don’t need to worry about venting much.
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In your photo of the connection here is what I am seeing, the hose has a JIC female swivel end that attaches to a 90 degree fitting. That has a JIC male end connected to the hose. That joint can be tightened with wrenches if it leaks which is doubtful. The other side of the fitting is threaded into a bushing. That thread is unknown but possibly an NPT or BSPP (NPT is tapered BSPP is straight). Then the bushing is threaded into the tractor which is probably a BSPP thread and needs an oring or sealing washer there.
I would guess if it is not vented it leaks due to pressure build up when it heats up. If it is vented I guess that the bushing or the fitting need to be sealed.
And you don’t need to worry about bleeding the hydraulics on these tractors normally. The air is pushed out of the system by the pump as you use the equipment. Operate the cylinders if they are new and they are filled with fluid. A new hose is filled like turning on a hose Bibb fills a garden hose. Don’t worry about it!