Thaylen script is written in glyphs, as is in evidence on the map of the Frostlands. The Thaylen in that illustration is simply transliterated English, and can be deciphered using the key in the image to the right.
Like in Hebrew and Arabic (and other semitic languages), the Thaylen alphabet is an abjad (i.e., all consonants, no vowels). The shapes of the letters in that alphabet, with all their hard angles and thick brushstrokes, have a similar aesthetic to Hebrew calligraphy as depicted.
The Thaylen people are renowned for smashing their consonants together when they speak, and this is reflected in their writing. Further, it is written vertically.
Their glyphs don't use Thaylen 'graphemes'. Technically, the most accurate name for the glyphs would be 'ideographs'; known to be used in Alethkar, similar or identical to those used in Jah Keved and Kharbranth. These may also be used in the Vorin kingdom of New Natanan and possibly in Herdaz as well, bearing a similarity to the writing system of Thaylenah and, perhaps, owing to a shared proto-language (i.e., the Dawnchant), extant across much or all of Roshar prior to the Recreance.
Therefore, the translation of the Thaylen script on the central portion of the map of the Frostlands is: 'Southern Frostlands'.
Obviously, the Thaylen people also utilize numerals. Just as many different nations on Earth employ Arabic numerals (1, 2, 3, etc.), it is quite possible that all Vorin people use the same numerals, even if their written languages differ.
Translations and charts credited to User:Harakeke.