You make it sound like Stasya had been a Cinderella until now having to contend with whatever scraps of attentions were left over 
. Valentina must have attended to her a lot prepare her for Senior and Junior Nationals and I am sure she knows how to distribute her attention fairly. She is not the first coach to have more than one successful student, plus Misha is reasonably independent. Maybe in a perfect world Valentina could devote all her attention to Misha (but then again, that may be too much for him).
The fact that Junior Worlds are in Taipei makes me rather worried because we all remember what a long plane trip and jet lag did to Misha. And Stasya had some trouble when she had to skate in Harbin (as did some other skaters on the Russian team who complained of sleepless nights and the like). Maybe seasoned competitors have developed strategies for coping with it but it's not easy when you are just starting out.
The quad lutz may explain the pop in the FS at Euros, but what about the SP? The problem began there. The FS pop sounded very much like a consequence of that first pop, leading to worry, overthinking and loss of confidence.
I think the top 10 would be an acceptable result this season if it comes to that. It is still very much a work in progress. Misha and Maxim's main task is to retain two quotas and such a placement would guarantee Misha two Grand Prix spots. As long as he does not make stupid mistakes and give away points like he did at Euros I will be satisfied and he should be too to a reasonable extent at least. And it's not like skating that program without avoidable mistakes under pressure is asking too much of him - he has already done that.
Last season Misha took part in a competition between Euros and Worlds, what was it? He so badly there though that I am not sure such an experience would be a net positive.
Someone on FSO was kind enough to put together a list of competitions for February/March:
14 - 19 Feb Bavarian Open (Oberstdorf, Germany)
16 - 19 Feb Olympic Hopes (Brasov, Romania)
21 - 25 Feb Open Ice Mall Cup (Eilat, Israel)
23 - 26 Feb Challenge Cup (The Hague, Netherlands)
28 Feb - 5 Mar Cup of Tyrol (Innsbruck, Austria)
10 - 12 Mar Coupe du Printemps (Kockelscheuer, Luxembourg)