It is accepted, although perhaps not in your exact attempt. I think příliš is better, but it is acceptable.
"To nebyla velmi dobrá kniha" is wrong? Is "a very good=příliš dobrá? I thinked that "too good"= příliš dobrá", or is it an idiom? Thanks.
"To nebyla velmi dobrá kniha" is accepted. You can say "This book is not too good", but I am not very sure about "not too good book", I do not like it.
I (native AmE) don't like it either. Saying "that is a not too good book"would be like writing "that is a not too good sentence." Would it be understood? Probably. Would it be correct? No. The tricky bit is that příliš pops up often as "too" or "too much" in translations, but "too" just doesn't work in this sentence. So it's good to know that it can also be used as "very" in certain contexts.
That is "Nebyla to tak dobrá kniha." (the completely direct translation with "taková" does not work that well in Czech)