Interesting! I wonder how that happened. I might have been something in an old version of the default airport that was carried over to later Real Taxiways updates, since my software won't automatically rename taxiway signs if the underlaying airport data changes.
I've been working on getting you a new file for KMEM for about an hour, but it appears that Asobo has changed how the external package builder works since last time I compiled updates for Real Taxiways, and it now causes the simulator's launcher to hang...
I think I have a working file for you now, but now the problem is getting it to you. These forums are very limited regarding what file types and sizes we can transfer for obvious security reasons. I've been meaning to try this temporary file hosting service that can host small files for a maximum of six days. Please try this download link, and just replace the corresponding file (it sounds like you already know where to find it).
KMEM.BGL
Let me know how it goes!