A radio announcer today used the word “enviousness”. To his credit, he immediately realized there was no such word. The word he was trying for was, of course, envy. But instead of shortening the adjective form back to its original noun form he extended it into a longer noun form. Is there a word for a word that’s been lengthened into a new form and then re-lengthened back into a new version of its original form? I was thinking hypernym might work, but I made that up myself.
Hypernym. I like it. 
Regarding your question however, I have no idea.
Admit it. You only posted this so you could display your new word to the world, right?
Sorry, ‘hypernym’ is already taken (it means a word with a similar but broader meaning, e.g. ‘dog’ is a hypernym of ‘terrier’). As for the original question, Bush Syndrome?
Well, he was wrong (scroll down; it doesn’t need a separate definition).
The OED gives cites starting from 1561. It seems to be rarely used nowadays, but is not listed as substandard or archaic.
I’ll note that they list “envy” as a synonym for “enviousness”.
It sounds like it should be the opposite of back-formation, but googling on forward-formation or front-formation only yields two relevant links, neither with any explanation.
“extraneous suffixicationism”? There was a pit thread on this type of word a few months ago.
The addittion of unnecessary syllables- that’d be prothesis, epenthesis and paragoge, then.
HTH
Sesquipedalianism perhaps?
Not exactly what you’re looking for, but close… This refers to the gratuitous use of (presumably pre-existing) long words, rather than the unnecessary creation of new words as you’ve described.
When someone uses a word that is too long instead of a shorter synonym, that is polysyllabic verbalisation.
Sadly, many people think that using longer words is better, and shows more learning. In fact, it shows stupidity. The object of speech and writing is to pass your thoughts clearly to other people. If you use heavy language, you merely clog their brain cells with glue, and they are slow to understand you, if they understand at all.
All the greatest writers and speakers use short, simple words, usually based in Anglo-Saxon rather than Latin, Greek or French. So, they say “start”, not “commence”. They avoid the jargon words that end in -ation, -ment and -ative, nine-tenths of which are over-blown words for simple concepts.
Wow, it was good to get that off my chest.