3. Maybe hold it in Europe and North America alternately - with the locals hosting it each time (and competing with the alternate, previously held one for the kudos). Asia /Far east is not ruled out, but I am guessing the majority here are probably based in Europe / North America.
The guests dietry requirements might make it impossible to host the party in a single country. Infofront insists on jellied eels.

You're right - it checks all the boxes except for one. I was raised on jellied eel. The lack thereof is a serious dealbreaker.
Similarly Scottish guests may insist on haggis, which is illegal in the USA as it contains sheeps lungs.
Other guests may insist on other exotic delicacies like the ones below that may be illegal in certain countries.





I think local delicacies will be the hosts preferred option, but I am sure in infofront's case - flying in some jellied eels will be possible. It seems it's a must.
Halvening party seems to be a popular option. Whether we go for a year after (for obvious reasons) - or 'at the time' can be decided, as can the continent.
In terms of a regular thing... A fun suggestion:
A little competitive sport for a cup might be in order each Halvening Perty (whether it's on a field of sport or around a table) with the WO Halvening Cup to be won or lost each time. Suggestions for the sport welcome - although I realise a cricket match competing for the Ashes of CSW is unlikely to happen. Sadly.
Sort of a Ryder Cup, WO style? Those in any teams (Host Continent vs Rest of World?) will compete in WO uniform of team-coloured T-Shirts with a their own hat individually printed on it - to be provided by organisers ofc. WO trophy to be engraved and awarded afterwards (by suitable 'celebrity'?) with the cup to be held until the next party.
The honour of a continent at stake may make it one to be worth winning, and glory will be played for, legends made...