Last week? Maybe?!

A week to finish plumping, then start scoping trichomes, maybe. If it is an evaporative humidifier, yeah it could have caused a 3-5F shift, but it won't be a large effect. This maximum effect depends on ambient RH% and volume evaporating per second, of course. The lower the RH the more an evaporative cooler impacts temperature, which is what a lot of humidifiers are - if it has a wick, it's the same exact thing as those evaporative coolers. As water evaporates, it absorbs heat. This is how sweat works... and why it doesn't work in 100% RH conditions. As far as the leaves.. have to feed it a more balanced diet... don't let it progress so far before attempting a diagnosis and fix. If you are "flushing" without a good reason, stop doing that, lol. If you have to you can crumble off the dead bits, but don't remove leaves unless the plant is about to shed it anyway. might as well let it suck it down, first. I'd wager potassium is on low side. if in soilless, crank K up to 180ppm, or if already there, that eliminates one reaction. Maybe something is locking it out...

There are multiple (long term) issues affecting this plant, but there is nothing you can do at this late stage to "fix" or alter anything. Just ride it out until harvest, it will be fine.

Humidifiers normally deal with water vapor aka humidity not temperature. Or does your humidifier also cool the space??? Confused why it got much hotter without it. If anything the humidifier I'm used to dealing with add more heat into the space vs remove it. In the end if RH stayed above 40% and below 60% its fine. plants look fine and I don't think you have much to worry about, the leaves that are damaged will not repair but its close to the end so its ok. Its going to be feeding less then it used to in the end life stages. Watch out not to burn them or overfeed.

Hi bud. She's looking good. As far as the leaves are concerned, I would leave them. If they are not causing any problems, let the plant feed off them. Leaves are full of nutrients. Hope this helps, even a little.