Approximations not working

[virtualvinodh]

tr.tr('tʾmšč', sc='Latn', to_sc='Phnx')

Actual output: 𐤕𐤀𐤌𐤎c
Expected Output: 𐤕𐤀𐤌𐤔𐤕𐤔

I think here the Latin is getting denormalized and the combining marks are moved. This shouldn't happen if the input is Latn.

tr.tr('ضچ', 'Arab', 'Phnx')

Actual Output: چ
Expected Ouput: 𐤕𐤔

I don't understand why چ is not being approximated to tš and then rendered as 𐤕𐤔.

V