Talk:sofa
I think you got the etymology wrong. the word suffa in Arabic is derived from the verb saffa, (line up, arrange in a line, arrange in an order); which is derived from the root seen fa fa of the same meaning.
Suffa as a noun in Arabic refers to two things, rather related. One is a room with three walls only open towards the courtyard and the roof is covered with wood/palm tree leaves/bricks (whatever) to cover it - one beside the other in the form of a line, hence the name. The room was used as a living room in houses. Later on the word suffa came to mean the room itself and the Turks used it also to refer to a living room. The name for this room was dropped (because it became confused with the other meaning - my guess) and the Persian word ewan was used instead (hence ewan in Persian is not exactly the same thing as ewan in Arabic although quite near).
The other meaning is basically something similar to what we know now as a sofa. it is a long seat made of stone or brick originally then in later centuries out of wood and cushions used to be lined up on it for comfort when sitting, hence the name. This name remained and some people still use it today, although not for a sofa but for the original fixed furniture.
For information you can check Lisan Al Arab, Taj Al Arous, Al Qamoos Al Muheet and Muheet al Muheet. But naturally you will get the semantics and etymology but not the historical information.
Suffa was never used for carpet (hence the meaning is wrong), I don't know what you mean by Diwan, if you are referring to the Arabic meaning then a dewan is like an official registrar or government office (example: the diwan of the ruler (rulers office) - the dewan of the census) so the meaning is wrong too.
I don't know where you got this etymology and semantics; but Arabic sources do not relate it to Aramaic nor to the meanings you gave.