So I work for an IT consulting firm (web development) and was hired by a customer 7 months ago for coaching Git, implementation of VueJS on the front-end and fostering teamwork with devs who'd been in their solo comfort zone for the last 15 years.
I asked for confirmation multiple times on whether they were sure they wanted to go through with a bigger investment in front-end. Confirm they did, multiple times.

After half the team's initial enthusiasm faded (after 1 month), the 'senior' of them who's worked there for 18 years on a single -in the end, failed- project got a burn-out after half a week of showing up (without doing actual work) from the stress, and started whining about it with management that has no technical clue whatsoever. This and other petty office politics lead to the dumbest organizational and technical decisions I've seen in my short 5-year career (splitting a Laravel app that uses the same database in two, replacing docker container deployment with manual ssh'ing and symlinking, duplicating all the models, controllers, splitting a team in two, decreasing productivity, replacing project management dashboards with ad-hoc mail instructions and direct requests).

Out of curiosity I did a git log --author --no-merges with the senior's name on the 2 projects he was supposed to help on, and that turned up... ZERO commits. Now the dept. hired 3 new developers with no prior experience, and it's sad to see the seniors teach them "copy paste" as the developer's main reflex.

Through these 7 months I had to endure increasingly vicious sneers from the IT architect -in name only- who gets offended and hysterical at every person who dares offer suggestions. Her not-so-implicit insinuation is that it's all my fault because I implemented Vue front-end (as they requested), she has been doing this for months, every meeting at least once (and she makes sure other attendees notice). Extra background: She's already had 2 official complaints for verbal abuse in the past, and she just stressed another good developer into smoking again.

Now I present her my timesheet for January, she abuses her power by refusing to sign it unless I remove a day of work.
Earlier this week I asked her politely to please stop her unjust guilt-tripping to which she shouted "You'll just have to cope with that!", and I walked out of the room calmly (in order to avoid losing my nerves). She does this purely as a statement, and I know she does it out of bad faith (she doesn't actually care, as she doesn't manage the budgets). She knows she wields more power over me than the internal devs (I am consultant, so negative reviews for me could delay further salary raises).

I just don't know how to handle this person: I can't get a word in with her, or she starts shouting, and it's impossible to change her (completely inaccurate technological) perception.