Is Buddhism hell falsely claimed on wikipedia? Thank you all for your kind answers to my questions. I feel that this community is really different from the others. If I asked the questions I made here in my country, I would be condemned heavily by now.

Back to the question, as Buddhist hell only exists in one's mind, therefore the information on wikipedia must be wrong.

Naraka

Or is it correct? Why does no one change it?
There are instances where painful mental states or experiances are called hell. [Patala Sutta] E.g. If I do something that might ripen in being born in hell you also get the hellish feeling here and now, [Maha Dukkha-k,khandha Sutta, Cūla Dukkha-k,khandha Sutta] and in case you are born in the human world  similar pains will be experienced. [Maha Kamma,vibhaṅga Sutta, Cūla Kamma Vibhaṅga Sutta]

A more vivid description of hell is found in Bala Pandita Sutta, (Yama) Deva,dūta Sutta and Deva,dūta Sutta. Neyy’attha Nīt’attha Sutta mentions that the Buddha uses direct and indirect languages. Though these destinations may exist some of the descriptions maybe parables so you can draw an analogy of what is there to a concept that you might be familiar with as Arana Vibhanga Sutta mentions that when teaching Dhamma you should use common and familiar language giving allowance to the audience or region they are from. This does not mean that the destination are only exist in the mind or they are parables to experiences in this world.

Also the Wikipedia articles seams mix and match from multiple schools. Also it would be an idea to keep these descriptions as per the wording of the Buddha and let the reader infer its meaning. 

With regard to the descriptions in the Suttas many of the experiences in hell will not have a description in common language as language is developed to describe what we come across in this world. What is mentioned would most likely give the best idea of the suffering involved in these worlds.