First problem I hit is comments don't work. The documentation specifically says text in parenthesis are comments, but it isn't accepted.
After some staring at the docs, I realize in all the examples, there are spaces. It turns out (Comment) is not a comment, but ( Comment ) is a comment. Because ( isn't a pure operator built in the language, rather there's a FORTH word ( that eats all words until ) is found. Holy crap. I never thought I'd say this but maybe it IS possible to self-host too hard