The laws say that where a contestant is "directly at fault", they should get average minus, "partly at fault" average, and "in no way at fault" average plus. There's no specific guidance in the laws (or elsewhere so far as I know) as to how to make these determinations. What I do is this: ask myself if a contestant was clearly "in no way at fault". If so, they get average plus, if not, they get something else. Then I ask if they were "directly at fault". IOW, did something they did or did not do lead directly to the problem? If so, they get average minus. If neither of these is true, then presumably they were partly at fault, and so get average, but I now check this by trying to see
how they were partly at fault. If I can't articulate it, I'm going to have to go back and examine "in no way at fault" again. I do this separately for both contestants (or all four, in an individual event) involved.
Note that if you give one side a particular adjustment, you don't have to give the other side the complementary adjustment. Rulings of average - average plus, average - average minus, average minus - average minus, or even average plus - average plus (in the case of TD error or other extraneous factors - think "earthquake") are perfectly possible.
IMO, when you organize a tournament, you have an obligation to state what regulations (and elections) under the laws are in effect. In some cases (for example, an ACBL Sectional or Regional) there is an explicit "default" established by the RA. There is, unfortunately, a bit of a problem for online games. The current law says
Law 80A1 said:
The Regulating Authority under these laws is
{a} for its own world tournaments and events the World Bridge Federation.
{b} the respective Zonal Authority for tournaments and events held under its auspices.
{c} for any other tournament or event the National Bridge Organization in whose territory the tournament takes place.
If a tournament or game is conducted online, whether BBO or elsewhere, and is not a WBF event, and not under the auspices of a Zonal Authority (such as the ACBL) it would seem that subparagraph {c} applies - but in whose territory is an internet game? I think perhaps the internet is a new, virtual territory - and there is currently no one in that territory who has been designated to, or is willing to, take on the role of "NBO". The role of RA then devolves on the Tournament Organizer (TO), i.e. the person or group running the tournament. So, bottom line, online the TO says what regs are in effect - and he should do so up front, in advance of the start of the event, so that players who may be unfamiliar with the particular regulations may review them. I think it's also incumbent on those players to do so - the "ignorance of the law is no excuse" principle should apply. Where there are questions, players should ask (ahead of time) or take their best shot and take their lumps if necessary.
Asking for "BBO-standard" regulations is asking for BBO to take on the role of RA. BBO does not want to do that (and I don't blame them). I suppose that a group of people could get together and produce a set of "BBO-standard" regulations, but I don't see that as having any official standing. It might work c.f. the whole "internet RFC" concept or it might not.
If Addicts is following EBU rules, that fact should be published in advance. Then non-English players can check the EBU rules and alert (or whatever) accordingly. NB: by published, I mean that the information should be available. Links will suffice; the TO need not create his own web page with all the pertinent text.