What editor do you use to code?
In your FastBasic code I see Atari special characters.
Special character can be inserted in FastBasic's IDE by pressing ESC key before a CTRL-something keystroke. I don't know if it is possible to lock the special characters insertion mode.
Anyway, I could use FastBasic's IDE, but my development cycle is different....
I use Ultraedit with a custom syntax highlight for FastBasic in my notebook, where I write the BASIC code as any other code with identation and comments. The source listing in the description page of every one of my games is the original one, except that comments were moved to a second column to group instructions, and the binary sequences were replaced by a placeholder to keep the listing clear.
Then, I parse the BASIC code with a small script I've programmed similar to dmsc's TBXL-Parser, which removes the comments, abbreviates the instructions, encodes some escaped hex codes into ATASCII (special characters as a binary sequence) and joins all the statements with ":", splitting before reaching the max length allowed for the required category. I keep a FastBasic IDE opened in Altirra with my working folder mounted as drive "H:" or "D2:" , so I can load the abbreviated PROGRAM.LST listing file directly into it without an intermediate ATR file, and then parse it and run to test.
But in early stages of the development and when I'm debugging, I just encode the source into ATASCII but do not join the statements in few lines, so I can use FastBasic's IDE to do small tests and tweak it a little in the emulator until it is OK, and then Update my source listing in the PC with the final changes. For long programs, I use F1 key in Altirra to accelerate the parsing stage
The hard part is when I try to fit instructions inside the 10 available lines, without leaving too much space at the end of every line, because that means that more FX should be done. Sometimes it is possible to change the order of the statements when there is no dependencies between them, but sometimes I have to split a long expression in two... It's like playing Tetris!!!
BTW, the development cycle for TurboBASIC XL and stock Atari BASIC programs is the same, except that the script to encode into ATASCII is a bit different, because the statements abbreviations are not the same and it insert line numbers (not required in FastBasic), and then type NEW, E."H:PROGRAM.LST (or ENTER from D2:) and RUN to test.