TN Visa - Job Title vs Description

I'm currently in a "Fellow" role at a University in Boston, although my job is basically that of a mechanical engineer. I've been working at the same job for the past few years under the F-1 OPT, which expires in a month. My employer (a University) renewed me starting this month. But since my Visa expires in a month, I need to switch to the TN. I'm planning to fly into Toronto and (without leaving the airport and being subject to isolation), fly back a few hours later, applying for the TN before customs.

The problem is threefold:

1. I have copies of my diplomas (Masters MechEng) and transcripts, not originals. Is this a major issue?
2. My job offer letter calls me a "Fellow", and apparently they can't change that. Would this raise red flags?
3. The only other documentation I believe I need, is a "TN supporting letter" from the employer (in addition to passports, I-20s, etc.) If that's true, where would I apply under a certain category like everyone mentions? Say I want to apply under the Engineer category, is this simply through this letter? Or is there a TN visa form I'm somehow not able to find?

Any help would be much appreciated.
Upon landing in Canada, you will be subject to 14 day quarantine. You can try explaining to CBSA your intentions but there's likely no way around it with airport arrival. Some people reported exception when doing flagpoling but that's at land borders, so you need to plan accordingly.

1. If you want a solid TN application, find or replace your original degree and transcripts. Photocopies can be given to CBP but you should have your original with you upon entry.
2. Internal job title and offer letter are not required for TN application.
3. Research on TN letter, it's specifically formatted and includes your TN job category, duties, amongst other things.

Read through more threads and research online, these are pretty basic requirements.
I think there's some ambiguity regarding the quarantine. I called CBSA yesterday. They said they only decide whether I'm let in or not, and could send me for PHAC screening if I'm sick. However, once I pass the test, they don't care. The officer referred me to PHAC to discuss my situation (airport flagpoling basically). The PHAC person said if I don't leave the airport I'm not subject to the quarantine, which was a relief to hear. Have you heard differently/personal experience @jixca ?
If you can do the turn at the airport then great.

I would still plan accordingly, if your application is found incomplete (like if the CBP agent wants to see your original degree and you don't have it) then you'll be stuck in Canada or the airport anyway while making adjustment to the application.
Yup, I'm giving myself 3 weeks just in case. But it would really suck for my job if I'm stuck for 2 weeks abroad, which is why I'm going to lengths to avoid it.

The reason I don't have originals is they're with my family, and my school won't issue a new printed one (only electronic official letter). My family thought it was too risky to send the originals by mail during Covid times. I might have to rethink that though...