Twb Wwyl H-ntyng Now

w (23) → j w (23) → j y (25) → l l (12) → y → "jjly"

Try : t→u, w→x, b→c → "uxc" w→x, w→x, y→z, l→m → "xxzm" h→i, n→o, t→u, y→z, n→o, g→h → "iou zoh" — no. twb wwyl h-ntyng

I suspect the phrase is encoded, but that doesn’t match length. w (23) → j w (23) → j

This looks like a simple substitution cipher (likely an ), where each letter is replaced with its opposite in the alphabet (A ↔ Z, B ↔ Y, C ↔ X, etc.). b→c → "uxc" w→x