Vishi, truly liked your post and reasoning very much - it's idealistic and how things *should* be.
But I disagree and not because I prefer Swara-Sanskaar. :(
Posting the why but putting it in tiny font, so you can skip reading it. :)
The sindoor falling entirely out of the dibbi is considered inauspicious, but the rectification is to gather it and put it back in the dibbi.
Here, the sindoor is partly in the dibbi, and even what's spilling out is decorously in a little pool still attached to the sindoor in the dibbi, so it's easily put back in with the rest.
It seems a way of saying Ragini's marriage is accomplished, because Ragini's sindoor and mangalsutra are not clearly visible.
The other way would have been to show Ragini already wearing mangalsutra and then applying sindoor to her maang.
And marriages are very rarely terminated if there's a scope for conservative orthodox majority-audience having no problem with the marriage continuing.