It is Trèves, today Trier, not Clèves (today Kleve). Trier is now in the German (Moselfränkisch) Dialekt area, but at the time given there were relics of Romance dialects in the area still spoken. But again, neither language explains that name.
In the submitted names database I found a Hebrew name Tchelet (f) "blue", but I cannot see how this name could relate to Tchélétis' name. In Tchelet (or Tekhelet) the "ch" grapheme corresponds to a /x/ sound, not a /sh/ sound.
--elbowin