Until Janette gets a genuinely talented (and young and fit) ringer, there is no way to know if she is to blame or not!
So far she's had 3 pretty difficult jobs on her hands - an older man that was universally disliked by show fans (and was only in it for the fake tan and glitter anyway), a middle aged actor who was largely disliked due to his role as a BAD MAN in a very popular TV show, who had littlel time to train, but as an actor was able to sell a routine (if he knew it well enough to feel comfortable performing), and PDuh, a desperate showbiz hasbeen, who has been reinvented as a reality "star" and is firmly resident in cloud cuckoo land, which at least protects him from crumbling in the face of the tabloid press.
As a strictly pro you take what you've got and do your best to shape the raw material any which way you can, whilst protecting your celeb, and showcasing their strength and deflecting attention from their weaknesses.
Yes, the "don't worry about the technique, concentrate on the routine" seems damning, but we don't know the context, maybe Jake had spent days struggling with the routine and there was either no time left to do anything but COME OUT AND GIVE IT SOME WELLY, or maybe Jake was really struggling to memorise a step sequence, because he was unduly worried about a small detail that most people won't notice anyway.
Besides, it takes years for actual dancers to develop proper technique, most (untrained) celebrities will never get anywhere near it, the pro just has to try and help 'em fake it.
Maybe Peter, having had smoke inexplicably blown up his ass by the judges for weeks, despite putting in mediocre performances, decided there was no need to make so much effort, and barely spent any of the last two weeks trying at all, believing himself to be bulletproof? You can't teach a pupil anything that they aren't willing to learn.
Ultimately, a Strictly pros job is to keep their celeb in the competition as long as possible, and considering Janette's raw material thus far, she seems to rather good at it.
As for whether she gets help choreographing or teaching, well, it's very common in dance to ask for advice and share tips, and of course ALL the dancers will occasionally need someone that dances the same role as their celeb to come in and demo or explain role specifics etc (hence Erin popping up in Kate and Anton's VT). As far as I can make out, there are backstage dance staff employed for the purpose of choreo support and Jason Gilki-whatsit is also available for consultation and critique.
Heck, we saw Gleb LEADING Anton in a Quickstep, while Anton made suggestions just last week, it's totally common and normal to ask for help, and the clip probably only made it to ITT for the sake of the Old Hand helps Hot Foreign Newcomer narrative.
I would very much doubt Aljaz secretly does all her choreo work, for starters, the pros get sent to wherever the celebs happen to be for the day job, so it's pretty unlikely that they see enough of each other. Especially this year, when they are both still in the competition.
(this reminds me of the "Kurt Cobain wrote all Courtney Love's songs" rumour, so I guess it must be a reoccurring theory for couples that work in the same business!)
As an aside, Janette seems to very well liked by the other cast and crew, and is often in the other pro girls socialising pics, is frequently mentioned fondly by Vicky Gill and as we've learned this week, is referred to by affectionate pet names by many, including Len, and is Natalie Lowe's favourite co dancer. Plus, Aljaz loves her.
I hope she gets some really good raw material soon, then we can all make more informed judgements!