****NEVER MIND ... just realized you are Air Force ROTC, not Army ROTC *** below answer would apply if you were AROTC.
If I'm interpreting the clues in your post correctly, you are currently approved for 5 years to accomodate your Engineering Degree as shown on your 104R form.
You're asking that if you switch to a Degree (Arabic) that takes the normal 4 years to graduate, would the new 104R that you would submit still showing 5 years be approved? I don't know. CAN you graduate in 4 years, assuming you might need a summer to catch up on some non-Engineering prereqs?
The general principal that governs your Cadre's and Brigade's decision is that the Army should not pay for more than 4 years unless necessitated by a major like Engineering. If you're not going to graduate with an Engineering degree, why would the Army want to pay for an extra year?