This seems a problem very similar the one we had in DEDataArrays.jl. See the discussion here: DiffEqs: Hybrid (continuous+discrete) system / periodic callback - #19 by ChrisRackauckas
In this case, we had a structure with a state and a set of parameters. The question about how propagate those parameters at each operation is hard to answer. @ChrisRackauckas eventually deprecated DEDataArrays.jl because it will be difficult to support every corner case.
Hence, given this past experience, I would vote for no metadata in DataFrames.jl. If the community wants, then we can add things to Tables.jl or another package.