Yes, you are right, downgrading from spine 3.6.37 to 3.4.0.2 leads to spine-sprites, where "inherit-scale =false" is noticed correctly by GMS.
Unfortunately spine 3.4.0.2 tells me, it can not load projects, which are made under spine 3.6.37, so either I have to rebuild my spine-sprites with all their animations from scratch or I have to wait in the hope, that sometimes in the nearer or farer future a GMS 1.4.xy comes out, which supports Spine 3.6.xy.
I think, the second option is the better one for me.
As I saw now, YoYo says under "required SDKs": Spine 3.4.02 (please use ONLY this version).
I am quite sure, the addition "(please use ONLY this version)" was not there last time I checked this page, and this was probably after the release of GMS 1.4.1772.
In the world of software it is a common technique, to make later versions of software compatible to earlier ones, they still grant access to earlier implemented features and add new ones, so usually it is said:
Use our software with files/plug-ins/tools from manufacturer ABC Version x.y OR LATER.
As "inherit scale" is a property, which stayed since a long time in spine, one would expect, GMS would manage it also from later versions of spine. But sadly it doesn't.
What GMS 1.4 and GMS 2.1 require instead, is a spine-Version from October 2016. In the meantime 3 major spine-releases followed, currently the newest one is 3.7.00 beta. It is normal, that one, who works with spine, would like to use the latest version, not only because of new animating tools and techniques, but also because the IDE is continously enhanced.
I both code and make artworks, but this is not the rule under game developers, as one can see in the sub-forum "Collaboration" of this website.
Usually programmers claim, they only can draw stickmans, while artists on the other hand avoid the prosaic discipline of coding.
So a GMS-developer, who contacts an art studio, have to say:
"I love the bunch of spine-sprites you made and all the beautiful animations. But would you please rebuild them with a spine version half a dozen versions earlier ? And for the same price, please."
This is, to say it in a general way, a very bad service to the customers either from YoYo or Esoteric Software or from both.