I am attempting to repair a hole in my wall but am unable to discern what type of material it is. Can someone offer advice please? Picture is attached to post in a file.

Hello. [b]Story:[/b] I'm renting an old soviet style apartment with a bunch of other people, where the kitchen has terrible wooden walls with red decorative tiles that all have deteriorated over decades. It gets quite dark in the kitchen, especially in winter. I have permission to do changes, but being a recent university graduate, I have a very small budget for improving something and major changes are not available because it would disturb roommates and be an inconvenience to them. I have a few days a month when they are not home and I can do some work. [b]Solution:[/b] Since changing the wood to tiles is both expensive and impossible to do by myself in a few days, renewing lacquer/varnish is difficult because I have no professional tools and the wood, as can be seen in the pictures, has a lot of deep crevices, so I just painted ivory colored paint on top of it. [b]Problem:[/b] Red decorative tiles. They look terrible with the new color of the wall. As a cheap solution, I want to cover them with waterproof photo tapestry, but the tiles have large gaps between them and I need an even surface to put up the tapestry. I wondered about removing them, but it seems like they hold the wooden wall and a large gap would remain upon removal. So I'm thinking if it's possible to grout such big gaps between the tiles and how to do it. I don't have exact measurements, but the gaps are big enough for me to almost stick my finger in between. Any suggestions? Tips? I'm attaching a few pics.