Some strategies I have generated have messages like this in MQL5 code:
cond[1] = sqGetIndicatorValue(!!! ADX_NULL_0_ADXLowerPeriod2 not found in [MACD_NULL_0_0_MACDMainCrossSgnFst_MACDMainCrossSgnSlw_MACDMainCrossSgnSmt, ATR_NULL_0_ATRRisingPeriod, ATR_NULL_0_ATRRisingPeriod2, ADX_NULL_0_ADXLowerPeriod, BOLLINGERBANDS_NULL_0_BBBarClosesPeriod_2.0_0, RSI_NULL_0_0_RSIPeriod, ATR_NULL_0_ATRFallingPeriod, AVGVOLUME_NULL_0_AvgVolumeRisingPrd, KELTNERCHANNEL_NULL_0_KeltnerChannelPeriod_1.5, HEIKENASHI_NULL_0, ], 1) < 30.0;
cond[1] = (sqClose("NULL",0, 1) > sqGetIndicatorValue(!!! BOLLINGERBANDS_NULL_0_BBBarClosesPeriod2_2.0_0 not found in [MACD_NULL_0_0_MACDMainCrossSgnFst_MACDMainCrossSgnSlw_MACDMainCrossSgnSmt, ATR_NULL_0_ATRRisingPeriod, ATR_NULL_0_ATRRisingPeriod2, ADX_NULL_0_ADXLowerPeriod, BOLLINGERBANDS_NULL_0_BBBarClosesPeriod_2.0_0, RSI_NULL_0_0_RSIPeriod, ATR_NULL_0_ATRFallingPeriod, AVGVOLUME_NULL_0_AvgVolumeRisingPrd, KELTNERCHANNEL_NULL_0_KeltnerChannelPeriod_1.5, HEIKENASHI_NULL_0, ], 1, 1));
cond[0] = sqGetIndicatorValue(!!! BEARSPOWER_NULL_0_BPPeriod3_0 not found in [ATR_NULL_0_ATRRisingPeriod, DEMARKER_NULL_0_DEMPeriod, ICHIMOKU_NULL_0_IchimokuSnkSpnCrsBshTnkPrd_IchimokuSnkSpnCrsBshKjnPrd_IchimokuSnkSpnCrsBshSnkPrd_2, DEMARKER_NULL_0_DEMPeriod2, STOCHASTIC_NULL_0_StochSlowDKPeriod_StochSlowDDPeriod_StochSlowDSlowing_0_0, BEARSPOWER_NULL_0_BPPeriod_0, BEARSPOWER_NULL_0_BPPeriod2_0, MOVINGAVERAGE_NULL_0_0_0_MABarClosesPeriod, TRSMA_NULL_0_0, RSI_NULL_0_0_RSIPeriod, SUPERTREND_NULL_0_1_SuperTrendATRPeriod_3.0, SMMA_NULL_0_0_SMMAPeriod, ATR_NULL_0_ATRPeriod, EMA_NULL_0_0_EMAPeriod, ATR_NULL_0_ATRPeriod2, HEIKENASHI_NULL_0, ], 1) < 0.0;
etc.
Naturally, they do not compile in MT5.
There are no such messages in MT4 source code.