Working with the standard templates can sometimes provide a problem, especially range limiting on a browse. The GROUP construct is a Clarion tool that delivers something like DATEPART() or TIMEPART() but the actual stored data on the server is still a single STRING, so you cannot easily break those components into a Key that can be saved on the server. On the server side you could have a separate DATE and a TIME field, that would then easily allow components to be in the key.
I did once added another DATE field on the server, filled at runtime as an exact copy of the DATE in the group, that gave me a template range limit on a key easily but that is a dirty fix since we now have duplicate data. A better alternative that I have done since is to manually control the filter in code at the “ValidateRecord” embed. e.g. do your test on the component and set the [BRW1:RecordStatus] = RecordFiltered. [You need to substitute the correct template generated name with Record:Status]
For sorting, using SqlDateTimeStr in a Clarion Dct defined key should not be a problem. If you want SqlDate in the key for range purposes, I believe you can essentially achieve the same results using a filter defined as:
SqlDateTime>=QueryBeginDate AND SqlDateTime<(QueryEndDate+1).