Lib Dems just delusional. Independents were the main beneficiary of the protest vote.
These local elections are not a reliable barometer for long-term politics. Turnout usually poor. Labour dodged a bullet by no Scottish council elections - that would have been a bloodbath for SNP.
Lib Dems are barely polling 10% in the EU election polls.
By the time next GE comes round UK will be out of EU in some form or other and the Remain issue will be sidelined. What could become an issue is after a couple of years people aren't satisfied that May/Corbyn "solution" is working then we could end up revisiting the whole saga again.
Local elections are not a referendum on the EU. But, there’s no way you can say that the Liberals didn’t have a good result. The fact that people used them as a protest vote and hammered UKIP shows that being 100% remain didn’t frighten voters off. Which it would have done if the will of the people really was purely for Brexit.