Interesting - last time I had my medals mounted the medalist contacted me to advise that the FRY clasp was also broken, and would I want it replaced? Presumably a production floor is these NATO gongs.
If you check the guide, the small dots of fabric glue are only used in the corners of the ribbon that are going to be buried under one or two layers of other ribbon / felt anyway, and it is only used to tack it down where it cannot otherwise be secured with the fabric tape or stitching.
The important thing is, wherever you do use it - make sure it's dry first before fixing another layer of ribbon / felt backing etc to avoid any chance of it seeping through. It is true what you say - glue and some forms of double sided tape will cause ribbon to discolour over time. Stitch wherever possible - it will take much longer, but as they're your own set it will be worth the finish.