Patrick: downloaded the file and dragged into a new Project. It opened (slowly) with 0 errors and 6 warnings. Mine is TBC 5 with the latest patch.
In TBC 4.12 it opened (much more quickly) and with 0 errors and only 2 warnings.
I exported from 4.12 as both a 2013 and 2018 DWG. Then dragged them back into a new project in V5. Both opened very slowly and both times TBC coughed up 34 errors and 0 warnings.
Sorry, that doesn't help much but it did open in both 4.12 and V5 versions. Odd that TBC 5 was very slow (more than a minute) and 4.12 was very quick. Also the difference in errors and warnings is strange.
Marshall