I'd use woodfiller so I could sand it smooth.

I want to thank you for the responces. I'm learning so much on this forum! SarsChlos...I wanted better airflow in the closet and thought the louvers would help. About 2/3 of the closet will be DH's work clothes, the other will be office files. This room is next to the main bathroom and will function as an office, reading room, and DH's dressing room. Strange! I know, but it's working for us this way. Annz...right now the bifolds are so clumsy and wobbly when we open them. Of course, if may be because they're 43 years old! I hadn't considered looking for "new and improved" bi-folds. Again, thanks for the good info.

I agree that mirrored doors tend to look "dated" no matter what. With that said, for mirrored doors, these don't look bad. I imagine the intent was to make a small space appear bigger. Any barn door would encroach on your space more than these doors. I don't mind the OP's inspiration barn door for this space, assuming other furniture ties it all together. However, on OP's application, they would be narrower and wouldn't look quite as balanced. I actually like the idea of wallpapering over the mirrors if it's done right. How about grass cloth or similar - either in a tone that matches your blacksplash or a grey tone? I would probably try to mimic the wall color as much as possible. I think that can look quite lovely and finished if done right. How much space is between the two doors when they slide past each other? A blog with mirrored doors covered in grass cloth in a lighter tone.

Found this one. Just Google “bypass door guide” https://www.stoneharborhardware.com/products/sliding-door-metal-floor-guide?variant=18477113868350&CATARGETID=120092900000011039&CADevice=t&gclid=CjwKCAjw1JeJBhB9EiwAV612y5StWxrYjMrUVzcSsi-FFjD7LQxftcWVQxEHhyeYhGyKZqs6YtRAaxoCCzwQAvD_BwE