I sincerely hope, Kimmi, that you are "particularly interested" in eligibility due to wanting to celebrate diversity and not coming from a place of wanting more scrutiny of who gets to call themselves what or what countries/ethnicities people are allowed to claim/represent. Unfortunately, the way you phrased this, Im getting the gist that you are more interested in critiquing the nuances of the "rules" or maybe even the enforcement of them. Thats a pretty dark path and your comment made me uncomfortable.
It seems like if one of your parents was born in a country (or one of their territories), you can play. Netherlands is getting good players out of Curacao and Aruba, 2 Dutch territories that are kind of independent but kind of still part of the Netherlands. It does not bother me. In fact, I think the diversity on the Netherlands team is cool.
Like Jazz on Britain, another example. Bahamas isnt part of Britain today, but it was when Jazz Sr was born there. And Jazz's grandma was a Bahamian softball star for 30 years, and for most of that span the Bahamas was British territory. The fact that Jazz gets to play for Britain and add diversity to that team is cool.
The rule is simply this, and it need not change: To represent a country/team in the WBC, you have to be invited to represent that country/team. If that invitation is made and the player accepts - you are on the team. Good enough for me.