I work in academic technology at Harvard, and my team supports an Omeka Classic service for our students and faculty. There is also a new digital accessibility group at the university, and have recently asked them to take a look at some of our Omeka sites to identify accessibility concerns. We did identify some issues in the admin dashboard, namely around color contrast, input labels, link clarity, and TinyMCE’s keyboard accessibility. There were some issues on the public-facing side as well, but we focused on a theme I made and that we have as a default: https://github.com/jaguillette/hvd-dh-omeka-theme
We plan to at least make some accessibility-oriented changes based on their feedback to our own fork of Omeka, but would prefer to make changes in a way that makes them easy to merge upstream, since they should benefit Omeka Classic users in general.
This seems like the start of a longer conversation, but I wanted to post here to get started, and make sure that our work is broadly applicable.