When I said to apply a filter before calculating a data point... I think that would already have been done by whatever implementation Zorro uses to deal with BarPeriod.

The current BarPeriod (grouping of ticks/bars) is based on time, whereas a Renko BarPeriod would be based on price. If that was handled properly, then I do think any indicator would still work and even display properly.

Since Renko implementation is really just a different grouping of price clusters, that is why I said it "should not be too difficult" to implement. Zorro is already handling price clustering bounded by time (for example tick data). This implies a multiple random number of datapoints could compose each single bar for the chosen BarPeriod. A Renko BarPeriod would be the same thing, only grouped by price range not timestamp.