Hey mainexpress,
It's odd, that's for sure.
Earlier, I asked you to confirm that those files were in the correct folders, and you did. I was just thinking: after you enable the mod(s) in JSGME, go into the actual matching game folders SH5installfolder\data\UserCharts\ and verify that those files are indeed there as well to make sure JSGME is indeed activating the mod and putting it in the correct locations. If they are confirmed there as well, then maybe they are corrupt like you said, who knows. If so, maybe go with your idea of re-downloading and installing again.
Another thought I had is to edit TDW's UserChart_Default chart in his Uis\data\UserCharts\, and add one of the entries from Sjizzle's charts to it like this one:
[Chart]
Category=Plotting Tools
Name=Maneuvering Board
Filename=maneuvering-board.dds
Size=-1,-1
Position=20,20
Draggable=1
ToolTip=Maneuvering Board
It will end up being:
[Chart]
Category=
Name=Flags
Filename=FlagChart.dds
Size=-1,-1
Position=20,20
Draggable=1
ToolTip=Flag chart
[Chart]
Category=Plotting Tools
Name=Maneuvering Board
Filename=maneuvering-board.dds
Size=-1,-1
Position=20,20
Draggable=1
ToolTip=Maneuvering Board
Back up UserChart_Default before you edit it of course!!
Reactivate TDW's mod again (with everything else in the proper order of course - save and load your mod list profile for this) and load the game to see you if get both Flags and Plotting Tools in his Default chart. If you do, this at least tells us that the dds files are ok. Don't forget to delete that and restore the backed file afterwards.
The other thing you can do is copy one of TDW's or Sjizzle's charts files, rename it to something like UserCharts_TEST.TDW, then copy some or all the other charts from the other Sjizzle charts into that. Delete all the other Sjizzle charts from the mod, leaving only UserCharts_TEST.TDW. Load up the mod and see if it works. Remember, as TDW said: these files must begin with UserCharts and have the TDW file suffix.
Let us know how that goes ...