There is an old style of Cyrillic, e.g. in the typeface Academy, in which the characters tse and shcha don't have the usual short descending mark (below left), but have swash tails (below right). I considered this for Scotch Modern (the face shown in the examples here), but abandoned the idea as inappropriate.
However, I am presently designing a more swashy typeface, and will include swash tails on tse and shcha. Would such tails also be appropriate for other Cyrillic characters which have descenders? Specifically, the tailed versions of zhe, ka, en, ha, and che:
And finally, if there is a swash descender on tse and shcha, why not on De?