I did just build the 6.1 on win 64bit (1.6.4 / 3.0.2) (I did not apply the patch, but that should not have an effect on SynEdit)
There is a warning about the search path. Apparently the project add the path of SynEdit. It should use the package instead.
But that does not seem to be the issue.
(Well actually it could be, it can lead to stale ppu files, make sure you check in your apps output folder for any synedit related ppu, and delete them)
I had to comment the 2 lines in HL-Lua. (it seems the ptruint trick will work here)
I did not get any error in syneditmarks.
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try in an empty project (without the lua code) to use the syneditmarks, and writeln the sizeof TSynEditMarkChangeReasons
It should be 4.
label1.Caption := IntToStr(sizeof(TSynEditMarkChangeReasons));