ジェーンはそのパーティーを楽しんでいるようにみえる。

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

party

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to enjoy (oneself)

in order to (e.g. meet goal); so that; take care (so as); hoping or wishing for something

to be seen; to be in sight; to look; to seem; to appear; to come