As far as languages go, I don't particularly care about English differences, and don't get worked up. British spelling is more elegant, perhaps. Some British names might be better, some American names might be. While a unified list in the end is a good thing, it'll be a bit of a loss of color if...
John I also don't fully understand your prior post - it reads as if you aren't aware of SACC and NACC?
Regarding the part I've quote above, I'm not sure what rules deem that old world vs new world have priority in anything? It sounds colonial, but again perhaps I'm not understanding.
At first glance it seems to be a formalization of what was already underway - IOC deferring to NACC and SACC for regional decisions, and eBird/Clements coming into alignment with IOC for old-world taxonomy.
For me, the greatest takeaway here is the unification of eBird and IOC, effectively -...
IOC combines forces w/ NACC, SACC, Cornell, and more to produce "global checklist"
Working Group Avian Checklists
A major IOU initiative
Building on the IOC World Bird List begun by Frank Gill and David Donsker...