This should be "o lukin e ilo sitelen!" for Toki Pona.

I changed it. Thanks.

I agree that "ilo sitelen" means "pen" and similar stuff ("palisa sitelen" is also used). With "tawa" you specify the type of the images, causing the relationship between the "ilo" and the "sitelen" to change, from a tool for making to a tool for seeing. That is, "ilo sitelen" may mean one or another "a tool for making images" or "a tool for seeing images". Using "tawa", the former becomes too improbable, thus leading only "tool for seeing moving images". But in toki pona, you don't need to specify if the images are moving or not, though nothing stops you from doing it. But "a tool for seeing images" can be (or probably is) a television, given the context (Tatoeba is contextless, so you can choose whatever you want).

Just remember that "ilo sitelen" isn't limited to be "pen" and the like, it means "image tool", just as "jan pona" shouldn't be limited to "friend", it means "good person".

Another thing to adress:
ilo sitelen tawa = a moving pen ( moving (image tool ) )
ilo pi sitelen tawa = a television ( ( moving image) tool )