Translation:Whom do you miss the most now?
If you're replying to who I think, that's not Middle English, that's Early Modern English. But kind of dog-middle-english. "Why doth thine app speaketh..." has do-support, which was very new and rare in Shakespeare's time. More apt would be to use "Why speaketh thine app..." Middle English would be more like "Hwi spekest thyne app" :)
I feel like it's not necessary to be so strict with time. I'm considerably more advanced of a speaker than this lesson and my most common translation error is omitting the "now" aspect of sentences that include 現在 because the present tense is implied in both English and Mandarin...
It's pretentious and unnatural in contemporary English, but technically perfectly correct. It's the direct object and takes objective case (which is mostly dead in English). You can rearrange it to "You miss whom the most". Try substituting a pronoun (since they do still decline) for "whom" to check case assignment. e.g. "*You miss she the most" is bad, but "You miss her the most" is good.
Why do you think that we may not start a sentence with "whom" in English? In this context, two interesting linguistic features separate Mandarin and English: 1) English morphology, although weak, does change (I/me, who/whom, he/him); Mandarin morphology does not (我/我, 誰/誰, 他/他). 2) English syntax allows WH- movement; Mandarin syntax does not. In English, we may ask "who do you love?", "whom do you love?", "you love who?" or "you love whom?" Mandarin does not allow WH- movement, which is why 誰 is at the end of the sentence.