>As for why "neun...und sechzig" is ambiguous: with that weird pause it's not clear if this is still 69 or literally "9 and 60" (which is what the word "neunundsechzig" means), i.e. 9-60.

9 und 60 vs. 9 hundert 60, if you speak quickly then the "ert" part of hundert is often swallowed, making it more difficult to discern between the remaining "hund" and "und".