@Catfish has just reported the following information about this bug, particularly that TOTPP does accept the continuous modifier, but it has to be in a specific location.
I should be able to write code to check events files for this particular error, and probably even produce a new, corrected, file automatically.
Just dropping by the forum and this thread caught my eye. So I tested it using ToTPP v0.15.1 and v0.13.2 (pre-Lua), Windows 7 64-bit for a couple of simple Flag/CheckFlag->Text events in a couple of scenarios, as well as for a few more sophisticated events in my WotR scenario. The Continuous modifier worked correctly in every test, although, unlike unpatched ToT, it appears (on trying to break it) that the ToTPP strictly applies the 'modifier must never be the last parameter of a trigger or action' syntax rule from Macro.txt. Ignore the rule and the game ignores the modifier. Apart from that I don't know what may be causing it to fail on other people's systems. Perhaps it's a Windows 10 thing.
I should be able to write code to check events files for this particular error, and probably even produce a new, corrected, file automatically.