>"Scots pretty much is a dialect of English that is phonetically spelt out - it's not surprising that a US teenager could write it."

No, there are a number of distinct linguistic features of Scots, and it has its own regional dialects, e.g. Doric, Orcadian, Shetland (which is also in part based on the extinct Norn language). See e.g. https://dsl.ac.uk/about-scots/history-of-scots/ (and sub-pages such as https://dsl.ac.uk/about-scots/history-of-scots/grammar/ ) for further information. Simply doing a dictionary-lookup word-replacement completely misses all of this nuance.