Yes, you would as \n is the line break character in ascii, but (a) it would still need to be replaced since it would actually be \\n by the way the message string is interpreted; (b) by default (no message system), it wouldn't work for messaging since it draws character by character and the draw_text method wouldn't recognize a \n character or do anything with it anyway (besides draw a square), so I would still need to add a condition for it; and (c) the default message system already uses \n[y] for the actor's name, and while it would be possible to use \n without [] to signify a line break, I didn't want to double up functions like that. So, (a) and (b) mean it is the same amount of work to use \n instead of \lb, and (c) means it would be confusing. So I think \lb is the better choice. Besides, most people wouldn't know what \n is generally in scripting and \lb for "line break" is, I think, more straightforward.
You still need to share that script though, even if that is all it does and I probably also need the configuration part of your ATS.. Or else just recreate the error in a new project and send it to me since, when I tested, I was unable to recreate your error. It might be a certain combination of features on that is causing the problem or it might be incompatibility with another script and your FF12 script is a likely culprit.
Ideal would be to recreate the error in a new project and send it to me, but I definitely need the FF12 script if you want me to fix this bug.