What the page does not do
Be clear with yourself about one thing: the page shows the start time with the zone label you chose. It does not work out each visitor's local hour and rewrite itself for them, and it does not detect where someone is. Anyone reading it at 22:00 in Reykjavik sees the same line as anyone reading it at 22:00 in Warsaw.
That is not a limitation to apologise for; it is a reason to write the time carefully once rather than hoping a tool sorts it out later. If you want to give people a diary entry, the confirmation email carries a calendar file and a Google Calendar link, and both are built from the time stated on your page โ another place where an ambiguous hour becomes an ambiguous appointment.
And if the audience is genuinely split across many hours, the honest answer is not a cleverer time format. It is two dates, which means two pages, because one page holds one session.