"The globalisation of the type market and rising interest in multi-lingual typeface design is a source of great optimism among many typographers. Yet despite the proliferation of these beautiful new typefaces, many still do not support some European languages, let lone cater for African and Asian languages. In fact, contrary to the claims of advertisements, the offering is, in respect to language support, quite limited."
David Březina On diacritics. Great article about a complicated issue.