I can't attest to the BLF issue as it has not been reported to me. I have several smaller installs using them, so perhaps it has to do with how much activity is present or something else.
I will agree that GS sometimes adopts a firmware release using a - "Ready, Fire, Aim" strategy and then looks for user feedback to see how the new aspects work and what they broke that did work before.
However, I am a little puzzled by the initial post wherein the issues are seemingly directed at 3CX yet; your last post reports that having followed the GS forums and seeing the same issues occurring on other systems to include Asterisk based, why you don't consider this more of a GS issue? Further, if GS is not supporting uCSTA and this is a needed feature, is this not also a GS issue?
Keep in mind, that GS is not a supported phone and that other makes and models, some non-supported, seems to work just fine.
Having said all of the above, I do wish that 3CX and GS could both find their way clear to collaborate again.
Hopefully, the dial string will help with the park issue and the BLF will be found to be something else. As far as uCSTA, well, that clearly seems to be a GS need to address.