I've not completely read all the articles you've cited, only briefly did I skim through some of them. What I did gather is that none of these things are concerning the engine - and the engine is exactly what I verbatim referred to:
"There's no extreme heat, no need for oil changes or air filter replacements, tune ups. Your engine starter failing is a thing of the past."
RE: Elon Musk Gets Largest CEO Pay Package (Ever?) For Running Tesla Into Ground