Add action block to update timeline columns in automations

There is no way to update a timeline column in an automation.
I’d like to have action blocks to update both the start and the finish dates of a timeline column. Could be one block for start date and other for finish.
Ideally, these blocks should allow setting these dates by an offset of “n” days before or after the original date in the column or before or after today.
If possible, make it work for columns in both items and subitems.

Please make this happen! It’s quite frustrating that it can only be accomplished with an app extension.