The phrase "are even more amusing" is correct and usable in written English.
It can be used to compare the level of amusement of two or more subjects, indicating that one is more amusing than the other.
Example: "The jokes in this new comedy show are even more amusing than those in the previous season."
Alternatives: "are even funnier" or "are more entertaining."
What's even more amusing, though, is that this is not the first time the book has been published in English.
"Pom Wonderful Presents: The Greatest Movie Ever Sold" is even more amusing than "Super Size Me," the documentary that put Mr. Spurlock on the moviemaking map in 2004.
"We've headlined here," says Joe Van Moyland before "Baby", the Jing Jang Jong's final song, surveying the pub venue whose name, in the specific context of Brighton, is even more amusing than his band's.
It's even more amusing when a third of it was done within the last month.
What's even more amusing is that all this time-wasting and panicking has all happened within the Republican caucus.
What is even more striking (or amusing) depending on your point of view, is the fact that rather than looking inward to find the root of such problems, many members of the party establishment seem to be looking for scapegoats.
While Festivus pole displays are certainly amusing, what is even more provocative is a group of Satanists who are attempting to erect a permanent Satanist monument in Oklahoma, because they already have a Ten Commandments display.
DEAR MOTHER AND DAD: I am forgetting my grammar rapidly, although there is one East Boston lad whose English is even more disreputable than he himself, and whom it is amusing to correct.
Brilliantly, the idea was green-lit and the whole thing is even more amusing/disgusting than anyone could ever have imagined.
Pnin's various scrapes and other escapades might be made even more amusing if they left him with hair tousled and spiked out of place.
