For Q2 we will have part of the feature - for the column headers only ( merged headers on many levels spanning over several columns).
Regarding the workaround - yes, retemplating the cell is the only possible approach with the current version . However I would recommend to put the heavy "multi editors" controls only in edit mode.For example setting the CellEditTemplate only. This way scrolling performance will not be hurt.
the Telerik team
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