"I'm happy to make an issue over this, it seems worth it."
Good, yes.
"because it's the festival they've gone ahead and done it anyway"
I don't think that is strictly true, but not clear what is 'true'!
As has been said upthread, if this had been 'look, this is the Festival City, a short push won't hurt you' it would be understandable - perhaps even acceptable to many.
BUT
Lesley made a big, public, deal of 'making sure a two way cycle route is maintained (and signed)'.
Even making allowances for 'reality' and deliveries, it has just not happened.
She has been made to look foolish and certainly not in control.
I have a certain amount of sympathy for her - there are bits of CEC that pay no attention to outside (or even inside) influence - bit like Network Rail (which LH has also tried to deal with).
However she is an experienced politician with a reasonable track record of getting what she wants. 'We' don't want to hear her saying 'look it's bad, but there is nothing I can do about it now' - but that might be more sensible/honest.
Of course the important thing is to make sure it doesn't happen again.
I have very little faith that can be done.
Just stop pretending/promising.