Nope, totally disagree with you. Latin would be required when dealing with the church and monasteries - it was when the Protestant reformation came into being that many nations decided to change church material and sermons from Latin to common languages. I suppose you could just wait 400 years or so till that happened. So, if you can't learn Latin, you ain't going to be much use with the largest employer of scribblers.You really seem to be looking for the turd in the punch bowl on this one. Most people, finding themselves in a place where they don't know the language, will learn the language, particularly if they have zero contact with anyone that speaks their language.
The curious thing about writing is that it is a very specific skill. While writers of Latin letters may have difficulty learning to write Arabic, the idea here is that the users of this site might find themselves in ancient London where the writing used Latin letters. So the shift is not really extreme. And going from never writing anything to writing is much more extreme than being an expert writer of one language to shifting to a new language.
Secondly, one could promote themselves as taking notes in a secret shorthand where you'd quickly write phonetically so that you could read it back later. Traditionally writing was taught as what we now call Calligraphy. Calligraphy is a very methodical, and beautiful writing style. Go back even 100 years to find countless references to the importance of good penmanship. Modern education teaches methods of writing reasonably fast. A modern person would be able to transcribe a sermon much more quickly and precisely than an 11th century monk. This shorthand could then be relayed to the monk to put into Calligraphy.
You would also have to be able to speak 1000 year old French to deal with the aristocrats - assuming we are in the UK.
And English at the time would require you to re-learn how to speak. Unless you were an academic, who perhaps studied Beowulf in its original form, it would sound like a foreign language to most of us ordinaries.
And how exactly is a starving weirdo who can barely communicate with the lowest serf, going to be able to find any 'study material' to get your writing started? There was no paper at the time - the first English mill was opened in the 1400s - vellum was the go to material to write on, and that was extremely expensive. Who is going to let someone who 'writes funny' and is struggling to talk, anywhere near a writing desk where there are people who have spent decades becoming expert with a quill and vellum, and know what they are doing? Since the advent of the PC and the smartphone, I've barely written anything nice on a piece of paper - some scribbles and workings sure, but really unless you have calligraphy as a hobby (another skill, I'd guess is relatively rare nowadays) we'd probably be boned there too!
You are really going to struggle very hard with the language in the 11th Century, unless you had specifically learnt something about the period and its languages.
The more you think about it, the more you realise how badly adapted we'd be to the time period. We'd have very few (possibly no!) skills that would useful. Knowledge of carpentry might be good, wood was everywhere....but you've learnt how to work wood with modern tools. Could you make a wooden plank from a tree trunk and an early medieval saw? It's going to be a bitter learning experience again, so you'd probably need to be an apprentice and start from the bottom again. If they let you!
Perhaps your knowledge of mathematics might wow them? I mean, proper algebra hasn't appeared in England yet, why not 'invent' that, then Cartesian coordinates, then analytic geometry and perhaps try and kick-start a scientific revolution and the Enlightenment half a millennium early. Well, you might be lucky, if you figured out how to speak, then impress the fledgling academics at Oxford...but, actually, I think you'd struggle. You'd be so far ahead of everyone that they'd probably see you as a crank. And I'm not even talking about really contentious things that we take for granted, like decimal irrational numbers (I would bet that all people at the time would not recognise them as actual numbers), but they didn't have negative numbers as a worked-out concept in higher maths (although they would have understood them in terms of debt and credit) or even the number zero at the time. Arab numbers were actually banned by some governments and mistrusted by those Europeans that had come across them. It would be an uphill battle. Even Newton in 1660 produced Principia Mathematica by looking backwards to the mathematics of Euclid and ancient Greek geometry. You'd have to re-learn all this stuff. (Hint, the deep philosophy between the medieval philosophy of maths and sciences was radically different from our current conceptions.)