What-is-equivalent-function-of-ConvertDateToBar-in-WL7

If you install the latest download of 6.9, the QuickRef will have many/most of the equivalent functions. In this case, use IndexOf -

CODE:
//In Execute(), where bars is the BarHistory
int n = bars.DateTimes.IndexOf(new DateTime(2022, 3, 8)); 

Also refer to this sticky post for a quick translation guide -
https://www.wealth-lab.com/Discussion/Quick-WL6-9-to-WL7-Translation-Guide-5548