The Modern Forgery Hypothesis

[ololololo]

Making deliberate mistakes seems crazy if you're desperately trying to make the document look real, no?

Perhaps there is a deliberate distortion to give the document an “exotic” feel. Well, overall, it’s quite possible that the author took the word “april” and ran it through the chain aperil – aporil – operil – aberil. 
This is a very simple method — you just change familiar words.
Learn to write in a similar handwriting? With a pen, this can be done quickly. I learned to write in Gothic script in about... a day (well, I started writing really beautifully on the third day).

However, there is a counterargument to all of this — the special abbreviations used for these month names.