reports suggest it cost hundreds of thousands of pounds to secure.
Could do, certainly, if they went the traditional route and hired a big firm of lawyers in the UK who then subcontracted the job to some equally expensive lawyers in the USA.
OTOH, this kind of stuff can be done quite cheaply, if you download the forms, fill them out yourself and just hire somebody to take them to the court. For an uncontested subpoena (as this was) you're looking at a range of a few hundred dollars (to pay a local ambulance chaser to stand in front of a judge for 5 minutes) down to as little as $50 if it fits one of the "accelerated subpoena" classes that Federal law provides for (there's one for copyright infringement, for example) where all you need do is get a local private investigator to put it in front of a court clerk for stamping.
Of course, I doubt that the council even thought of going the cheaper route. So that's a second charge of wasting public funds on the charge sheet, then.
Also, since councils can't sue for defamation, and given that they're probably planning some "alternative" form of retribution rather than honestly intending to follow through with legal action in CA, there's the question of whether they made a bad faith declaration in their demands for a jury trial, etc. in California.
Incidentally, I also find fault with the way that they've set out several of the counts, in that they've been sloppy about where the act began and where it ended (they really only needed to show one of those was in CA, to establish jurisdiction) and proving harm to the defendants "in the state of California" would seem difficult since it's unlikely that any of them have a reputation there to be damaged.
And the paragraph numbering looks messed up.