Going back to spelling, I was a bit dubious of the example given of a word with five consecutive consonants - cmrlj which is Slovenian for bumble-bee - first off, "lj" is a single letter in Slovenian and second I think the "r" is basically functioning as a vowel there. (If you are trying to say it to yourself, remember that "c" is pronounced "ts".) However there is no doubting the authenticity of the Dutch word with eight consecutive consonants, angstschreeuw - linguists may cry out in fear and horror that "ch" is a single phoneme, but it is spelt with two letters. (Again, if you are trying to say that to yourself, remember that "s" and "ch" are pronounced distinctly in Dutch, unlike in German.)
Like the TV programme it is based on, the book is a little too pleased with its own cleverness, but fun all the same.