There is an extra halant after every character in this keyboard type although it doesnt exist much in Punjabi. We can use tilde for halant is those 3 characters.
When we type single characters it should not be ਸ੍ ਦ੍ ਫ੍ ਗ੍ ਹ੍ ਜ੍ ਕ੍ instead it should be ਸ ਦ ਫ ਗ ਹ ਜ ਕ on conditions when no vowel sound it attached.
Select Transliteration Tool and start typing. We have to add an extra "a" after every character. That increases the number of strokes so this is not appropriate.
Tilde has already been coded to type halant. So it can be used if we want to put halant which is used only with 3 characters.
Are you speaking of this input method: https://github.com/wikimedia/jquery.ime/blob/master/rules/pa/pa-transliteration.js ?