Indirect formula ist currently only half implemented. Only A1 referencing ist possible. The R1C1 referencing is not implemented even though it's explained inside the description of the function itself (2nd parameter of the formula).
In dynarange you cannot use indirect formula colums. Only for rows. The exact use case is bit more complicated to explain but basically this makes it possible to control indicators for expansion collapse feature.
Thank you for your great idea. While we cannot commit to a specific target version, we will consider adding it to our future internal backlog. If you can add further information about the context of this feature, please add it here so we can evaluate it more fully.