Hi Chris
I feel it's up to how people are defining cusum. For me it could be a cumulative number based on the whole time series. It equals to sum an auto date histogram of a certain metric from begging of the specified timefield until now and when date range filter is applied, it's just slice a piece of data from timeline instead of re-calculate it based on the date range filter. There might be needs for both cases, I just hope if kibana team could add a variable in cusum function to make both possible. Now, if this is not possible, I'm looking to see if it's possible to build custom function for timelion...