Unicode exists to support what people use. Do people use Latin script for Tatar? Evidence indicates that they do. Should Unicode support it, then? Certainly. Does Unicode support it? Yes, Unicode supports the Latin script, with gobs of extensions. So what's the problem?
Latin n with descender, which is not encoded but needed according to <http://www.eki.ee/letter/chardata.cgi?lang=tt+Tatar&script=latin>.
For Tatar, at least, it's OK to use eng as far as I can see.
Official usage is n with tilde. See, e.g., the language law of 1999, which is available online and which uses n with tilde throughout: http://tugan-tel.noka.ru/belem/imla
However, I was in Tatarstan early this year, and signs etc. frequently show inverted e and n with descender where the law would call for a with diaeresis and n with tilde. It's pretty much of an alphabet in transition.
Philipp
