Do you remember what gcc errors were like just as clang got popular? They were pretty bad before the c compilers started competing to have nice ones.
Those are wonderful in comparison to the errors in LaTeX.
Fucking extra newline breaking equation* and causing nonsense.
In general complaining in such terms about a project you've just taken over doesn't seem very professional.[2] We've all been there, done that, etc. LaTeX diagnostics are atrocious. All received large projects are filled with decisions one wouldn't have made oneself, and consequences one would have avoided. But it pays to remember that any senior engineer has presumably left in their wake several large projects that befuddled and frustrated subsequent maintainers, both because of regrettable reasons, yet also for reasons that one would readily defend.
But to suggest Microsoft Word as being a superior option... I can't even begin to fathom such a comparison. I can imagine, however, how insanely frustrated and pissed I would be if I had to take over the task of managing a huge, complex Microsoft Word document. I'm also prepared to admit that there may exist a universe (in which I might be living) where Word is a defensible choice over LaTeX, and that the choice might be more akin to common religious preferences--vi vs emacs, CLI vs GUI, etc--and not something that can be strictly judged in objective terms. Hopefully that admission would give me pause before I let loose such a tirade.
[1] AFAIU, Jens Gustedt was the previous editor, both initiating and executing the switch to LaTeX. But I've never participated in the committee. I may have had a mistaken belief about who was doing the editing over the past several years.
[2] That's a comment on the article, not on the author himself. Professionals do unprofessional things all the time.