You may have actually uncovered a serious bug here.
Investigations point to a potential failure to set path vars on initial load, hence why it loads on every other try.
EDIT:
Ughhhhhh. Debugging this stuff is horrible. I might just rewrite the algo again.
Can't hurt to add some proxying in there for proper detection.
EDIT2:
Few adjustments made.
Settings.txt in a char folder now loads before anything else (kinda important for tweaks to actually take effect whoops)
blockCharData tweak added to do just that, prevent char codes in a SWF from loading.
Using the tweak:
With your folder results in a consistently loading background.
In the future, just use BG.png argh.
An alternative solution might be to proxy vanilla code loading, concat each new code on to the end and finally add our Code.txt to the very end. That would retain all loaded properties and allow overriding of vanilla codes.
But that requires effort.
I'll push a test version after documenting this stuff and perform a proper release later.