Does anyone know whether there are combined unicode characters for vowels with tilde below? I could only find them for ḛ (U+1E1B), ḭ (U+1E2D), and ṵ (U+1E75) but not for any other vowels. I'm not looking for the combining diacritic (which puts a tilde below any character) but was wondering whether there are other characters (a, o, y, etc.) that have unique code points with the tilde below (used in IPA for creaky voice).
Searching this page on the Unicode website for "tilde below" confirms that the three characters you have found are all the characters with tilde below in the Unicode standard. For others, you have two resorts:
- Use the combining tilde below (as you already noted)
- Use the private use area for them
Proposals for their addition to Unicode will be turned down as the Unicode consortium currently does not consider more precomposed characters for inclusion in the standard.