Thanks for the C2 effects import feature, it works well.
After import, typically I have to do a couple changes to the effect shader code to make it compatible with C3 uniforms and sometimes C3 sprite sheeting, but it's not too difficult.
Here are some notes on C2 effect porting, based on some of my recent experience:
construct.net/en/forum/construct-3/plugin-sdk-10/dropshadow-effect-ported-c3-142753