Re: A question for the experienced.
Enough time has elapsed that you qualify in many ways as a beginner. There is nothing wrong in approaching things afresh, and representing yourself (self-identifying) as a beginner.
At the same time, nothing is served by hiding relevant details from your past, and I can't imagine any offense committed by disclosure. Hopefully the admissions process will allow a two-way interview, formal or otherwise. That would be a good time to tell your story.
Rank is its own issue, and that is for the dojo community to assess. I've long viewed rank as a kind of currency -- tokens inherently worthless yet representative of perceived value. Exchange rates among aikido groups are often ad hoc.
It's fine if they value your rank at parity; it's fine if they determine your currency to hold no meaning in their system; it's fine if it's recognized, but depreciated.
It's up to you to see to it that, over time, your investment accrues appreciation.