Thmyl Lbt Jyms | Bwnd Llandrwyd Mn Mydya Fayr

Still nonsense. But note llandrwyd — Welsh has ll as a single phoneme, dd as voiced ‘th’, wy as ‘oo-ee’ sound. This suggests the plaintext might be Welsh or pseudo-Welsh .

y → i or e a → unchanged? f → f? r → r. So fayr = f a y r → f a i r = fair. Works. mydya = m y d y a → m e d i a = media. Works perfectly: y→e and y→i? That’s inconsistent unless y maps to both e and i — impossible for simple substitution unless one plaintext letter maps to two ciphertext letters (unlikely).

t (20) → q h (8) → e m (13) → j y (25) → v l (12) → i

Shift of -5:

t (20) ↔ g (7) h (8) ↔ s (19) m (13) ↔ n (14) y (25) ↔ b (2) l (12) ↔ o (15)

qejvi — nonsense.

lbt = l b t → ‘l b t’ — maybe ‘lab t’? ‘lob t’? Or ‘let’? l e t → l y t? No, l b t → if b=e, then let? No, b would be e? Unlikely. thmyl lbt jyms bwnd llandrwyd mn mydya fayr

Check fayr — if Welsh, ‘fair’ means ‘next’ or ‘beautiful’ (soft mutation of ‘mae’). mydya — ‘myd’ (meed) is not Welsh; but ‘my’ = my, ‘dya’? mn — in Welsh = ‘if’ (os, not mn). bwnd — in Welsh = band? ‘Bwnd’ not standard, but ‘bwn’ = load, ‘bwnd’ might be ‘bwnd’? jyms — not Welsh (no j in traditional Welsh).

t → s h → g m → l y → x l → k

thmyl → gsnbo — no. Test shift of -3 (common in puzzles): Still nonsense

thmyl → lymht (no) lbt → tbl jyms → smyj bwnd → dnwb llandrwyd → dywrdnall mn → nm mydya → aydym fayr → ryaf

But apply ROT13 to all:

Maybe the cipher is: each letter shifted by -1, but with vowels shifted differently? Unlikely. y → i or e a → unchanged