Evaluating an identifier which constitutes the end of a line in an editbox, aka the last token, results in the editbox being "glitched": the newtline sequence is eaten as well as the first word of the next line or everything from that position onward.
Evaluating $cr, $lf, or $crlf also result in
* No such identifier: $crlf
* No such identifier: $lf
aka the error message itself has a literal newline sequence in it, coming from the misinterpretation of $crlfCD etc.
Courtesy of maroon, you can use that to quickly test:
//clipboard AB foo $!crlf $+ $crlf $+ CD bar $!len(if.next.line.has.2+.words+only.eats.crlf+1st.word) $+ $crlf $+ EF foo $!CHR(33) $+ $crlf $+ GH bar $+ $crlf $+ IJ foo $+ $crlf $+ KL $!len(deletes.all.following.1.word.lines.until.line.has.2.words) $+ $crlf $+ MN $+ $crlf $+ OP $+ $crlf $+ QR foo $+ $crlf