Well here’s how you’d do it, the only piece i’ve left out is how to truncate the titles, as i have no idea what length or amount of words you’re aiming for..
https://wordpress.pastebin.com/YzzNSyRv
What the code above does is unregister the original recent comments widget, then registers a new one, under a slightly different name, but utilises the settings from the original widget (so you don’t have to do anything in the admin, it will update your existing recent comments widget).
All that’s left is to customise the code, i’ve put some comments by the area that needs modifying.. which looks like so..
// YOUR TITLE TRUNCATING CODE GOES HERE
The code can go in your functions file (your theme’s), or alternatively i can convert it into a plugin for you (so you can download and activate, if you find that easier).
I’ll also help with truncating the titles if you let me know the specifics of how they should be truncated… ie. what length or word count ..
??