If your program, with the chances suggested before, works for all cases and will never or very seldom need to be changed, then it's probably not worth pulling out a big powerful tool like a parser generator module.

If it's likely to change much, even a little at a time, then eventually you'd have saved more and more work in the end by moving to using one. It's all a matter of cost versus benefits.

If everything works and never needs to be changed, then the cost of rewriting the code to use another tool is wasted effort with no real up-front benefit. If someone needs to maintain it, then the costs add up over time either way and the benefits of having a cleaner implementation become more pronounced.

BTW, I've had enough French and Spanish and your comments are written clearly enough that I get a good understanding of them, although I wouldn't be able to rewrite them en Portugues. Yet another example of why clear comments are helpful -- non-native readers have a massively better chance of making sense of them.