It depends on the dialect, in some places ج is pronounced like a g (Egypt I think), in others you'd probably use ك since it's the closest. ريجا was a weird one, like many people in the comments pointed out
There is a letter گ that is used in other languages, and I've sometimes seen it used to represent g in proper names, but it's not a sound that natively occurs in Arabic (except for ج in Egyptian, as mentioned)
The audio is very synthetic and I don't think it helps. The woman who has done the examples up until now is quite clear maybe another text-to-voice synthesizer could be found to take the load off of her though.
This has probably been asked elsewhere, but the audio adds an "un" sound to the end of the word, but does not when I open this discussion page and play the audio from here... there is no meaning to this extra syllable correct? It is just an audio bug?