I 100% agre with 3run, this is your best option, but also i totaly understand your problems. Try contact support did you can upgrade to A7 commercial. I am sure that they will help you if you explain your problem. If not, try open topic, maybe someone want sell A7 com licence.
Then you will solve problems with shadows. About shaders... there is no great solutions for c-script.
But at leasts you can try mix your c-script and lite-c, and use shaders like bloom, dof,... I think this with mixing c-script and lite-c, work only in versions A7.5.

BTW: Don't scared try translate whole code into lite-c, this can be done faster than you think. Just try, if you stuck somewhere community will help you.