Interesting, that sounds like more is going on. I have not had any issues with Photoshop CC 2019 other than just learning some new behaviors. I am running Mojave on my Macs and it has been flawless. I would do a full uninstall and re-install the apps.
Just as an FYI, transform works the exact same as it always has when using Shape layers. The change is when using raster graphics.
I spent 9 years retouching full-time for a portrait studio and my hands are glued to the Shift-Option key, so I know it is really hard to unlearn the habits that are like second-nature to us. For whatever reason, I still think the change is a good thing. You can still use Cmd and grab the corners. You just hold Shift if you do not want to transform proportionally.
Not trying to convince you, but I actually think it will speed things up in the long run.
Happy to help if I can.