I was beginning to think that there was some theoretical relative ridge length that couldn't be ignored for safety reasons.

I have a gable roof over an area that is attached to the main building (it sits below the roof line of the main building).

At the far end of that extension I have a concrete slab roof projecting at right angles over another building (it projects within the length of the gable).

I wanted to add a gable connector to the existing gable roof in order to provide for better (i.e. more height) access to the concrete slab and an overhang (i.e. create an L shape of gable roofs, no hips).

It seems to me to be a perfectly straight forward thing to do, apart from the fact that you cannot modify the ridge length.

It looks like you are suggesting that I have to draw one panel on one side of the main gable and several on the other just to produce a gable sticking out at right angles from another. Pretty poor.

In plan view, imagine a gable roof running left to right. Now add a gable connector at right angles to that (and within its left/right boundaries) with its ridge touching the first ridge, with a different pitch and extending out from the first roof a short distance.