Hi Johan,
I believe I encountered something like this a very long time ago in a very large medical application. If I’m remembering right, I had added a new table or possibly even just added enough to an existing table in that large dictionary and encountered what you presented.
I ended up creating a second separate dictionary and moved a few tables that were not related to any other to that second dictionary thus freeing enough space in the primary dictionary to keep related files together. Having two dictionaries did not present a problem. They were completely independent. I believe there is a 64k limit on the dictionary space.
Now my memory could be getting a bit fuzzy on this as it could have been maybe 15 years ago or more.
I still use c63-9058 for a very large veterinary application and agree with you on its solidity.