*All* translation is difficult. The successful translator has to assimilate the ideas from one text and render them in the other. This, as the Wikipedia article (
The acknowledged difficulty of translating between two natlangs is compounded with Lojban as a target because the vocabulary is severely limited. Typically the translator has to spend a lot of time in the satisfying but (for me) slow and difficult work of coining new {tanru} and trying to decide if it's appropriate to convert them to {lujvo}. Or, when Lojban is the source, of trying to unpack the original author's {lujvo} and interpret the sense of her {tanru}.
Go to
www.lojban.org, click on "Texts in Lojban" and read for a while...