I'm using Creator 4.1,
Attached is a test where i set the ParamB to false by default, then set it to read only if ParamA is false using a ternary operator $ParamA == false ? true : false on the Read-only field, if ParamA is true then you can change ParamB value.
See attached image and project.
Hope it helps
One caveat with my test:
When you drop the component on the schematic ParamB is false as you asked, then you can set ParamA to true, with this ParamB can change it's value, lets say you set it to true, then set ParamA to false and ParamB becomes read-only but it's still set to true not false as you requested.
Carlos, I see what you are doing. I got to the conclusion that it is not really possible, but on the other hand, I think just using error warnings seems to work well enough.