Angelien

Angelien is not a Dutch diminutive of Angela at all! You see, -ien does not exist as a Dutch diminutive suffix: the closest possible diminutive suffix is the archaic -lijn.

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Instead, Angelien is actually a more phonetical spelling of the French name Angeline. It is used by parents who want to ensure that their daughter's name is always pronounced in the French way (with three syllables), because a lot of Dutch people (especially in the north) will pronounce Angeline as: /ɑn.ʒə.'li.nə/ (with four syllables).

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And that brings me to the next point: the pronunciation that you have listed for Angelien is partially incorrect. The correct pronunciation is:

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/ɑn.ʒə.'lin/

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Also see X-Mar's comment from February 2006: she too shows that there is no /ŋ/ in the pronunciation.

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Sources:
• -lijn: https://en.wiktionary.org/wiki/-lijn (in English)
• https://en.wikipedia.org/wiki/List_of_diminutives_by_language#Dutch (in English)
• https://nl.forvo.com/search/Angelien/nl/ (in Dutch)
• https://youtu.be/cLdluIJrObs (in Dutch; the name is said at 0:03)
• https://youtu.be/nEduxs-ZNOU (in Dutch; the name is said at 0:29 and 1:03) [noted -ed]