I would definitely wash it out of my wall hangings. I would just use a different washing method, probably just soak them until the glue was dissolved, and then a couple of rinses, no agitation and lay flat to dry - or I would make the wall hangings able to withstand a regular washing. Heavy starch is not good for fabric over several years no matter where the fabric is. If these are seasonal wall hangings that you plan on discarding after a few seasons, don't worry. If they are something to keep then you need to get the starch/glue out of them.