According to
ISU Communication No. 2111 (2017/18 list of officials) it looks as though there are 500-600 or so ISU or International singles and pairs judges.
In addition, there are thousands of national and lower judges in various federations around the world who are not (or not yet) authorized to judge international competitions and who also need to get up to speed on new rules.
Most of these judges are never going to judge skaters at the world medal contender level this year. Or if they do judge senior B events attended by top skaters or national championships in federations that have contenders, they'll get to judge one or two of the top skaters in an event with lower-ranked contenders, not all of the top ones against each other.
All of these people need to get on the same page regarding what the new rules are and what they mean.
There are 4
singles and pairs seminars scheduled for 2018 (one was in April, so it wouldn't have covered all the new material).
These ISU Seminars are primarily for the Officials of the Host ISU Member. However, Officials of other ISU Members (not more than 2 per ISU Member) can also attend subject to the availability of places.
So not every international/ISU judge is going to attend a seminar each year. Those who are actively judging will get updates on site at the events that they judge. Maybe there are e-mails that go out to all judges on the international rolls -- I don't know.
Non-international judges in various federations would need training in their home countries.
To the extent that the trainers at local seminars or the referees at international or national competitions have more information about what the technical committee is aiming for with the new rules, a lot of the learning would doubtless happen in these in-person situations. But not every judge would get the same live examples to discuss.
Then there are also ice dance and synchronized skating judges, mostly not the same people.