In your opinion, what are the most important features that even the most famous and accurate translation websites lack?

We cant get proper meaning of a text by using  website because of some term word differs from the direct meaning.

in general, websites lack functional translation , they focus on literal translation or word by word translation.

Also they don't use the techniques of translation like paraphrasing and find a suitable equivalence.

I have noticed that translation websites work as a quick took to pull up the terms and equivalents that a translator may need in the translation process, but I can say that they usually fail to  reduce the time and effort involved in the entire process because a translation website does not analyze the structure of the source language and reproduce the text in smooth structures and proper word orders or strong formats. I agree literal and out-of-context translations yield some messy translations by these websites, hence the inevitable need for human intervention. I keep reading a note by some websites asking for feedback or input on the given translations, but I see little improvement by the passage of time. 

Belal

There isn't any accurate translation through all websites. You should revise it before use it officially 

I think they cannot provide an accurate meaning ofthe translated text 

They don't use technical tearms in many websites and they tende to give a near translation for the words and tearms in search , and also for some languages such as the Italian one they don't give accurate translation

Losing the targeted meaning of the original text is the main problem because websites more or less depend on ltteral translation; they don't dive into the deep meaning of the word.

In fact ,translation of websites normally has some technical terms , in which  hard to find one word meaning in Arabic for . which force us to use the use of the term or an Arabic meaning which is not very familiar for too many people .

i think that website can't accurate perfect meaning

                                                         because we cant get a full meaning of a text because of some term word 

differs from a direct meaning

Exact meaning and accuracy ,sometimes differ