I would rip out everything..including the fabric and start with a clean slate..

Those are "volunteers". As said above, rip it all out. Landscape fabric is a nightmare. If you want to suppress weeds stick with cardboard or newspaper topped with mulch and/or Roundup. OT, you have beautiful original windows. Please keep them.

What are volunteers? Funny you think so about the windows, I wouldn't call them beautiful. And they don't open, so we actually would love to tear them out, but don't have the $$ for it at the moment...

Volunteers are plants that have just seeded themselves naturally. Why don't your windows open? Nothing you replace them with with be as beautiful or ecologically sound.

It looks like someone took french doors and mounted a bunch of them side by side stationarily, so they're not really windows and theyre not really doors... It's a sunroom, so there's 5 full length windows on that wall. We really want to have the option to get air in

sorry to be so full of questions, but what do you mean by ecologically sound exactly?