I sympathize with the goal but accessibility benefits would be far
outweighed by maintaince costs. We regularly use grep to find code which is
about to be deprecated; wikis copy gadgets from each other; more
experienced developers are sometimes asked to help a wiki where the local
maintainers have less experience. We have a whole global user group for
people who go from wiki to wiki and fix things.
And that's not even taking into account the implementation costs, which
would probably be massive if it includes stuff like localizing
Lua/Javascript language keywords. The Wikimedia community collectively has
a lot of experience with web development but not a whole lot of experience
with programming language compiler development.