FWIW, Although I haven't been the the UK in decades and have no connection there I'm a target of two UK lawsuits alleging hundreds of billions of dollars in damages on basis that would be difficult to impossible to domesticate where I reside.
I had to make the difficult decision either to ignore them and potentially risk arrest if I found myself in the UK and risk my assets being seized if they ever ended up under control of a UK exposed entity (perhaps due to an instution I use being acquired by a UK entity), or to fight back and expose myself to legal costs which could be ruinous even in the (likely) case that I win, creating a serious risk that I could lose by virtue of running out of funds. (A situation the claimant has even bragged publicly that he intended to create).
Fortunately there was charitable support able to cover the legal costs, which made the decision somewhat easier but nothing will ever compensate me for the astronomical amount of my time the litigation has taken up and the stress its subjected me to.
The SPEECH act is a big improvement over the prior situation, but unfortunately the ability to abuse the UK for SLAPP isn't limited to libel lawsuits. I think we need a generalization of the SPEECH act that bars the enforcement (and turns obtaining a judgement into a domestic tort) of foreign judgements in jurisdictions that don't have comprehensive anti-SLAPP protections.
But even with that there remain fundamental challenges. As a victim of malicious litigation I'd like it if the courts better regarded bringing false litigation as a tort and had more facilities to require the claimant to post security for not just cost but for substantial damages in case their claim is found to be false. But policy like that would dramatically reduce access to justice especially for parties with limited means. You're not going to sue big-bad who genuinely harmed you if losing means paying huge damages, especially if you'd have to post security for it.
There is probably no complete solution to using the courts abusively.
We're fortunate to live in mature civilizations that are stable and safe enough to give us an illusion that the universe is somehow fundamentally fair. But it isn't: nature is red in tooth and claw though we try to hide it. Sometimes a bad person can harm you and yours gravely and there is absolutely nothing you can do about it except try to pick up the pieces and move on. This is obviously true when you consider attack with a gun or a knife (nothing can undo a death or serious injury), but anything can be a weapon if you're creative enough-- including a court.
But that doesn't mean we can't try to do better.