A newbie can start their journey about extension development.
Yes it will be possible as @Kumaraswamy stated above. Atleast some would be possible if not everything.
"Can a AI2 developer help a Android Studio user ?" 
The errors can be converted into "Human understandable" Text.
Though your question is offtopic but, ya, ofc an extension developer know java, and java is used In Android Studio too
Java is full of code, annotations and errors, so do u think u can do so? and wrap all of dem in "Human understandable" as u stated?
I didn't tell Extension developer I told a Appinventor User. 
Some errors are similar to each other and can be classified into similar categories to Readable language.
But I said for Extension developers, maybe u missed my post
Appinventor for the current moments are used to learn. He does not teach Java, teaches logical thinking, solving problems, he also teaches the use of loops, conditions, etc., by the way he can compile the code to a real app, which more encourages to learn. I do not think Appinventor should serve to professionally writing Apps, but I know that some do it, they even look for solutions to change the name of the package. According to me, the order is such, learning to block in Appinventor, next extensions in Java, next Java + Android Studio. Of course, if someone wants to professionally create apps. If someone creates simple apps for yourself and your friends, Appinventor is enough. I think even a database of extensions created so far is sufficient to create anything. I do not think it is sense in creating another "programming language" which will be transformed into Java. What was not this language, the beginning of programmers and so they will have to learn it, and they will have problems with him. According to me, there is no programming language that will be thinking for the programmer.
Extensions are used to just "extend" the ability of what Apps created with AppInventor can do.
As you said AppInventor doesn't teach Java but teaches "logical thinking and solving problems". Java or any "real" programming language teaches you how to "think" or also more than what you stated.
If apps made with AppInventor should not serve an app professionally then, what are those extensions we/anybody created for? People could just have used the webview component instead for every UI related extension and other things avaible 
(joke).
It makes some sense, it just not splitting texts and words and putting them all together.
Java is just very complicated to just print a statement that would take 5 lines of code (non-android) when you could just do it in a line in Python.
I don't think it's that bad to do it than limited inbuilt functionalities.
I do not consider it a joke, very often this method is recommended in the community as a workaround.
Then why we make extensions 
We won't do everything in the webview either. Let's face it, the era of extensions ended a while ago. Now many extensions are repeated, we rarely see an extension that hasn't been there yet. I think, now this serves more to try Java than to extend AppInventor's capabilities.
The current era is of UI extensions. 
So implementing someone else's external library without granting a credit, writing a few annotations and other lines of code and assigning all the work to yourself.
Josiah
Drag and Drop Blocks - that is coding, just uses a different interface to other coding methods. To get anywhere with a Project, you do need to know how to code it.
making an extension with blocks may be very complicated, but I think that if more tutorials on how to create extensions appear, new extension developers will have an easier time getting started.
Just, a simple tutorial by me, its in hindi
Ok idk how this blew up so fast, but here are my problems.
It would be better to see the Installation Wiki in the Rush-cli GitHub repo.
nice project and this can be done with python and with other stuff but lack of knowledge i dont know javascript and html css for GUI interface.
this is possible but not eveything provide in block but like a user can chose which block he want to create and he can give a code for that block or he can use provided nodes (blocks)
nice project i will look further if i create something like that it should be super easy to create extension.
Appybuilder won't compile.
You can use niotron ide
Ya the big method with combination of methods. Means the group of blocks is single block.