I don't agree with everything this person says, but the "da" being pronounced as "za" makes sense. Thats why some people write Ramazan and some write Ramadan(more on the arabic letter below)

The following note I found on https://www.sikhawareness.com/topic/18823-when-to-pronounce-dadda-%E0%A8%A6-as-za-%E0%A9%9B-how-to-read-guru-granth-sahib-part-3/  -

Dadda as Soft Th- or Z

Special Dadda.

 

ਨਦਰੀ

Pronounced as Nazaree

ਕਰਮੀ ਆਵੈ ਕਪੜਾ ਨਦਰੀ ਮੋਖੁ ਦੁਆਰੁ ॥

karmee aavai kaprda Nazree mokh(sh) duar

ਨਦਰ - Notice how we pronounced the ਦ as Z - Nazar.

Mokh(sh) - This will be covered in a future lesson.Just like how Dadda sometimes make the Z sound, Khakha sometimes makes the Shatkone sound.

 

ਹਾਦਰਾ

Pronounced as Haazraa

ਹਦੂਰਿ

Pronounced as Hazoori

ਗਾਵੈ ਕੋ ਵੇਖੈ ਹਾਦਰਾ ਹਦੂਰਿ ॥

Gavai ko vekhai Haazraa Hazoori

 

ਕਾਦੀਆ

Pronounced as Qazeeaan.

ਵਖਤੁ ਨ ਪਾਇਓ ਕਾਦੀਆ ਜਿ ਲਿਖਨਿ ਲੇਖੁ ਕੁਰਾਣੁ ॥

Vakht na paayo Qazeeaan je likhni lekh kurann

Why is the n there? Here it is plural so we add a bindi to the end indicated by n.

If Guru Sahib was calling out to a Qazee "Hey Qazeeaa" then there would be no bindi (n) sound.