AH!! As I understand you need to look at the Besieged Map to find out the status, no way to compute it exists.
This sounds a LOT like weather (other than how to obtain the information -- NPC .vs. map). As there is a weather page, why can't there be a Besieged Status page, too. It would reflect the status of the Besieged Map every say 15 minutes, until meeting certain criteria and then it would do it more often. Example might be: Training - Preparing level 7 check every 15 minutes. Preparing level 7 - Advancing: check every 5 minutes. Advancing and Attacking: Check each minute.
Of course there can be overlap (e.g. Trolls attack and undead advancing) so the timer would need to go with the shortest period.
This could be an open web page (as is weather) or say for those with a PAID Guildwork account.
Anyway, IMHO, it would be great to have it -- even though Besieged is no longer the great thing.
Hey, maybe a campaign status could be part of the service / website!!!
I.B. Halliwell