A friend of mine (Russian national) got issued a Schengen visa by Finland. In her application the purpose to visit Schengen was visiting her grandmother in Finland. She entered Schengen by train to Helsinki.
She also traveled to other Schengen countries (partially by air), and she had her final departure from Schengen from Vienna.
That departure was a few months ago. She has now been granted another Schengen visa by Finland. However, the visa came with a written note inside the passport that if it is found that Finland is not her main destination, she may be refused visas in the future. This note was not present the first time around.
She is now worried about flying within Schengen, as she wonders if the visa authorities can access her flight history and deduce/assume from it that Finland was not her main destination, even if that's not the case.
For example, if she flies to Stockholm and goes back by another means of transportation, she worries that visa authorities will simply see the flight to Stockholm and deduce that she might have spent more time there than in Finland.
Is this concern well founded? Do the people issuing her future Schengen visas have any information regarding her previous flights within Schengen? Or are the entry/exit stamps the only thing that matters?
To clarify, she does not intend to lie. However, if she flies to other countries at all, she is worried that this may give a misleading image to officials. That's all.