Hello Epsilon or is it Ipsilon.

You are quite right. The Greek Theta hails from the Hebrew Thet. In Latin script languages they use the "TH" combination. In the Karmeli alphabet I introduced the real Thet. The capital letter is instantly recognizable, the small letter is the hand written letter, of course mirror reflected.

All the new letters are styled to fit well the rest of the alphabet.

Regards,

Michael Avinor.

Actually, it's "Upsilon" (the 20th letter of the Greek alphabet, written: Υ or υ).
In ancient Greek this letter was pronounced "oo" (like in "room"), but later the pronunciation changed, and that's (I guess) when it got its Hebrew name.