Finolia wrote:Hello I hope it's ok for a native speaker to butt in.
As you said "ich lern" is colloquial (or the imperative) and "ich lerne" would be the correct form. We just use it in spoken German or while chatting which is more or less speaking. As you said, you should never ever use it in a formal (in fact in any) text.
We often drop the final -e when we speak ("ich hab", "ich komm", ...) and since it's used to shorten words it wouldn't change anything if you would use an ' instead of the -e. That's why we don't use it in written German. In fact, the apostrophe is more work than simply writing the -e!
But I think you can use it if you want. Since it is "wrong" (colloquial) anyway there is no rule (as far as I know).
And since we drop it very very often (in spoken German!) it kind of IS "super common"
It's funny, I was almost going to say something like, "I hope a native German speaker pipes up..." That is really good to know, I kind of figured that was the case, but it's good to hear that from someone who speaks German natively (I would have been equally pleased to have heard from a very proficient L2 speaker who is in German speaking environments on a regular/constant basis).