Problems Iâve dealt with in the past include non-legible characters being included accidentally in my YAML files by cutting and pasting. These are sometimes hard to track down.
Fair enough, but who gets to decide what is legible? The Unicode standard currently has 150 scripts, with more proposed. I doubt there is a living person that finds it all legible. And as for punctuation and non-orthographic symbols, well, they are certain legible and can sometimes have useful meanings. Even emojis can used to categorize node templates.
I think the best way to avoid mistakes is 1) to ensure strong, strict parsing at all levels, both YAML and TOSCA, and 2) create and use data types with appropriate constraints, e.g. if you only expect a >0 int then make sure to constrain, or if you're specifying a DNS hostname don't just let it be "string" but rather a pattern (regex) constraint that will protect against invalid names.