Are repair manuals and wiring diagrams region specific?

[veso266]

Hello there, I have EU specs VW Golf Mk8 R-Line and I am trying to retrofit AM Radio into it (because it doesnt have it and I need it, even if u use VCDS to enable it there is clearly something missing because the signal is awefull (this is the strongest station on the dial which always had perfect signal, but here its bearly receivable): )

I found out that the NZ spec one does have AM Radio:

So I was wondering are the wiring diagrams and repair manuals between EU and NZ universal or is there anywhere I could find the differences so I could figure out what module my EU spec one is missing

I already found what I presume is a wiring diagram: ,

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and inside I found that I need something called R177 Amplitude modulation (AM) frequency filter

But I am not sure if the this diagram is the right one for my car and how to figure out if this box is realy whats missing on my car, maybe my car has also a different antena amplifier that blocks AM frequencies

I also foound the repair manual: ,

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but inside there is no mention of R177 Amplitude modulation (AM) frequency filter so now I am realy confused, do NZ vehicles have its own repair manual?

Is there anywhere where I could find this out, because VW vehicles clearly have this its just that the one I can buy in my region (Slovenia) is clearly missing something

Thanks for Anwsering and Best Regards