(Vintage Story prelease v1.22.0-pre.1 dropped in the middle of working on this, and because I am eager to play with 1.22 and because I don't want to faff about with building for both .NET 8.0 and 10.0, as of this writing I do not intend to make a v1.21-compatible version of this mod. The source is public, fill your boots if that's your cup of tea. :D)
I've gone ahead and done the legwork to support the v1.21 stable client!
https://mods.vintagestory.at/closedcaptions
This mod adds closed captions for sounds in the game, with some configurable display options, including some colors for dangerous sounds, and icons for (mostly?) creatures/animals. Similar sounds get grouped together as "unique" (like there can only be one weather caption displayed at once).
Hypothetically it should be easy to add captions from other mods -- the configuration is patchable using JSON patching. Can filter based on categories in the configuration.
More screenshots!
It wasn't until I went to post this that I caught that someone else has been working on a closed caption mod -- so shout out to @Diff and his Captions mod too!! Accessibility is near and dear to my heart, and I love seeing that someone else is working on something like this. (Wish I had seen before now, but here we are! :D)