JavaScript cannot be ambiguous because there's a constant acid test: Does the machine find it ambiguous? If it does, it fails to parse. (If it parses, it wasn't ambiguous, but it still might mean something the programmer didn't intend.) That property will hold until we do something like embedding AI in the compiler.

Humans can deal with ambiguity. There are various reasons for humans to want to be ambiguous, and any natural language has to support that to be useful for day-to-day conversation. Loglan and Lojban might well escape that, if they're only ever used in contexts where ambiguity is not desired and will be repaired if it is found.

Think formal specifications, not love letters.

Isn't the automated insertion of semicolons to your detrimemt a result of ambiguity in the language, and the compiler forced to decide

The rules for automatic semicolon insertion are defined by the language spec.