Seems there was a bug upon further testing, so I've reverted the script back to the old method for calculating higher timeframe rsi values.
Unfortunately it means there will be the "stepping" factor caused by a type of repainting that will only grab rsi values from the close of the higher timeframe.
However, this doesn't make the script un-useable as you can still get a fairly accurate idea of where the rsi is from any higher timeframe conveniently from whatever chart your viewing from, and in the end this indicator is primarily for that exact convienience.
Also, the heatmapping of the rsi is a real nice way of getting a feel for whats going on at a quick glance. Personally I like to set up 4 different rsi timeframes that are still close together, such as 5/15/30/60 mins as an example, and then turn on heatmapping for the avg of all 4 whilst still only displaying the rsi for my current chart. This has brought my perspective back and saved me many many times.