Nope, It would just be super complicated with not much benefit. Proprietary custom indicators are not included in Forex Robot Factory, but we are pretty certain that our tool can find better strategies without it.
Just give it a try! You have to broaden your mind a little for new possibilities, we have so many students who start our course being glued to some strategy idea and indicator they have but then they realize it was their biggest mistake.
There are trillions, or better I say sextillions or strategy variations possible in the FRF. Don't be stuck to one idea which probably will not work anyway like most of the strategies. FRF will find the best strategy combinations for you and show which ones are robust.
I assure you there isn't some magic indicator that's gonna make a difference.
The other reason why there aren't so many custom indicators in the app is because of backtesting. Complex and non-standard MT4 indicators usually produce backtests that don't match with MT4 strategy tester results. Having the standard indicators gives solid and reliable backtest results that match MT4 environment.
My biggest suggestion to students it that you have to broaden your horizons, the generator will find strategies with simple indicators that you will never with complex ones.