how does it hold up?

would be cool to make a similar graphic on the gradual loss of the Old Norse case system in North Germanic

this ^
Phonology isn't the area where Icelandic is the most conservative, I would argue. There's a lot of transphonologicalization, but also a ton of innovations. Morphology is the main area where Icelandic's archaicness starts to show

pretty handwriting

Wiktionary says the word might be an Aramaic loan (from zaləmṯā 'man')

I've heard several claims online that broken plurals were originally just collective nouns, which grammatically functioned as feminine singular nouns. Is this related to the PIE-thing, or is it just a coincidence?

Why is [ʏ] used in the nynorsk example? Isn't it [ʉ]?

I mean sometimes people have to. There are a lot of Norwegian names that are notoriously difficult to render in Arabic, often to the point where it's just easier to use a different name. 'Inna' for 'Ingeborg' springs to mind