thanks for the report! i was finally able to get back to tat for some updates, and your reports have been very helpful. i've added a feature that should help with this in the latest release: https://ultraparadiso.itch.io/tat/devlog/853651/v030-release
the sounds list and the images list each now have an eyeball button that you can click to toggle their visibility. so if you click the eye on the sounds list, it'll hide the sound area visualizations and you'll be able to select images that were completely covered. there are a few artifacts still that i need to fix (the edit handles don't get hidden) but it should help with the issue you describe here.