Hello,
The default parameters are set to what is believed to be a generic setting that can be applied to every pair/index/timeframe that there is and can give an overall market sentiment and trend.
Trying to have fine-tuned settings for specific pairs/indexes and for specific timeframes/periods is not something that I can provide, this would the job of the trader. You can play with the settings as much as you like and you can find something that works better for you.
Personally, I use the regular candlesticks in order to look at price action and I have not a lot of experience in Renko charts.
For your chart above, my take without knowing anything about what pair is this or what renko range, the signals that you have in circle would be the initial shorting signal, but for me the confirmation is the MBL cross.