So, I've tried a few of the above-mentioned suggestions and still no luck. If I open a 2017 drawing that has one of my custom titleblocks in it I can click "Update" and it'll make it usable and editable which is great. BUT, of course it won't let me export or save the titleblock out into the folder where the other standard ones live for future use so I have to use this one in a blank drawing template file. Which is ok, but completely defeats the purpose of the tool and means I can't work on an old drawing that may not have a title-block and then put one in.
I went through DCapp's 11-step process which seemed promising, but when I got to the Title Block Data Link part it wouldn't let me put in my custom info and left me with "1" in every field even though I typed in a custom name etc. I get that all of the standard drop-down fields that you can select for fields are well, "standard" to someone, but the whole reason I am using a custom title-block is that all of our fields are pertinent to our shows. So there are fields like "Show Name", "Venue", "Load-in Date", "Load-out Date", "Producing Depot" etc.
I've tried copy/pasting my titleblocks into the "Standard" drawing and although everything there looks identical between my files and the ones that VW saved in there, they won't show up in the pull-down.
I'd love to actually USE 2018 but I don't have several hours to devote to fixing it so I can do a simple drawing.