SC2Mapster

Set the owner of the Regenerating unit to owner of entering unit, so then you change the owner to owner of (Regenerating unit)

That's even easier, When you create a boss bar, set the health to an Invisible unit of X amount of health. it always has 1 Health, when your capping a point, set health to +1 every second, when you leave the zone, set health back to 1..

That should work.

Create Variable
Set Variable to:
- Preset
Any Region

Unit - Any Unit Enters (Region(AnyRegion))

Edit - Not Create Region, Create Variable. Lol.

Create a Region variable, and set the variable to Any Region.

So you can still have it as 1 trigger.

You can set any unit enters any region

If then Else
If
(Triggering region) == Forest nWe control
Then
Unit Group - Add (Triggering unit) to Units To Convert
        Variable - Set Number of Units = (Number of Living units in Units To Convert)
        General - If (Conditions) then do (Actions) else do (Actions)
            If
                (Abs(Number of Units)) > (Number of Living units in (Units in (Triggering region) having alliance Enemy with player (Owner of (Triggering unit)) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))
            Then
                General - While (Conditions) are true, do (Actions)
                    Conditions
                    Actions
            Else
        Unit Group - Remove (Triggering unit) from Units To Convert
        Variable - Set Units To Convert = 0
Else
If then Else
If                       
(Triggering region) == foresrt sEe control
Then
Unit Group - Add (Triggering unit) to Units To Convert
        Variable - Set Number of Units = (Number of Living units in Units To Convert)
        General - If (Conditions) then do (Actions) else do (Actions)
            If
                (Abs(Number of Units)) > (Number of Living units in (Units in (Triggering region) having alliance Enemy with player (Owner of (Triggering unit)) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))
                   Then
                General - While (Conditions) are true, do (Actions)
                    Conditions
                    Actions
            Else
        Unit Group - Remove (Triggering unit) from Units To Convert
        Variable - Set Units To Convert = 0
Else

Etc, etc, etc