This seems like it has the potential to overlap with the scope of the Scientific Extension, at least at the Collection level...

This extension adds the ability to indicate from which publication data originates and how the data itself should be cited or referenced.

If this becomes its own extensions, should there be either a restriction or a best practice that attribution and sci:citation must match for Collections?

Scientific citations (usually in scientific publications) and attributions (usually in maps) are pretty different.

For example, the OSM attribution in Leaflet is simply

(c) OpenStreetMap contributors

On the other hand, the scientific citation would be more like

OpenStreetMap contributors. (2017). Planet dump retrieved from https://planet.osm.org . https://www.openstreetmap.org .

This example is taken directly from OSM, see https://wiki.openstreetmap.org/wiki/Legal_FAQ#I_would_like_to_use_OpenStreetMap_maps._How_should_I_credit_you.3F and https://wiki.openstreetmap.org/wiki/Researcher_Information

We can probably give such an example in both extensions to make the difference clear.

To discuss and potentially close at the Sprint.

Discussed and agreed to be put in the core.

We discussed it again due to discussions in #1278. The mixture of CommonMark and HTML is an issue. We should test and evolve this in an extension.