you can not convert mq4 to mq5 for renko chart generators,
mt5 renko is very different from mt4, you will be unable to convert it, don't waste your time with that
moreover, renko is not as good as it looks, it filters out time, but that's about it, time is important so you lose a lot of information
those offline charts for MT4 are generated from an incomplete tick history, or if they are generated forward, they will look different on each broker (due to different injection of tick data at highly volatility events) ... and you can easily lose them, they can be rewritten by the generator from a "simplified" history of 1-minute candles