If they failed, that shows that their influence isn't something that should keep us awake at night.
Tommy Robinson has been gobshiteing round the UK for years now. Why is he now suddenly being name-dropped in a discussion where some people are alleging - without any compelling evidence - that the American far right is having a significant influence in the UK?
As a reminder, the OP posted a link to a very poorly written Guardian article which alleges that some libraries in the UK have been asked to remove some books about LGBTQ topics and this is evidence of political interference by American right wingers. It neither specifies which books libraries have been asked to remove, nor identifies the people who have requested their removal.
If you know more than a gnat's fart about gender critical feminism in the UK, you will know that it is highly likely that most or at least some of the books in question are books which glorify self harm and promote the falsehood that humans can change sex to children, and that the people campaigning for their removal are likely to be left wing feminists, gay people and clued up parents who have educated themselves about this stuff. As such, it almost certainly has the square root of fuck all to do with the American far right, and a lot more to do with British people reasonably believing that these books are not suitable for children.
It's also worth noting that trans activists in both the US and the UK have made a real concerted effort to ban and cancel books by gender critical feminists such as Kathleen Stock, Helen Joyce, Hannah Barnes and others. Not to mention their attacks on children's authors such as Gillian Phillips and Rachel Rooney who don't toe the TWAW party line, and widespread calls to cancel the Harry Potter series, which have obviously failed because JK Rowling is too big to cancel, but it certainly isn't for lack of trying. But FUNNILY ENOUGH that doesn't seem to be troubling any of your pretty little heads.
Obviously none of this has got anything to do with Tommy Robinson, but in the absence of any evidence to support the original point, random shit flinging will have to suffice.