The spelling of the word "Taen" may seem unusual, but it is phonetically accurate. It is pronounced as /ten/ with a short "e" sound. The "ae" combination is a digraph commonly used in Scottish Gaelic and Old English where it represents a long vowel sound. However, in this case, it represents a short vowel sound. The word can also be spelled as "Ten," but the "ae" spelling is a valid alternative. Regardless of the spelling, the meaning of the word remains the same.
A poetical contraction for taken.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.