And once again "Გ" is not really an "uppercase" letter; it is just converted from "გ" using the **old** uppercasing mapping (whose use is deprecated in Georgian, but has been kept in Mediawiki).
An no, "Გ" is not some control character, it is another letter from the (Aso)mtavruli alphabet (considered to be an "uppercase" letter, only if we accept that Georgian is bicameral); while "გ" is the Mkhedruli letter (considerd to be "lowercase", only if we accept that Georgian is bicameral).
Using Georgian scripts as if they were bicameral is highly debated and in fact not even recommended (this is a matter of opinion and author choices to prefer the bicameral view, or the unicameral view).
For the modern Georgian language, its official script is monocameral, Mkhedruli ("lowercase" only) and converting Mkhedruli ("lowercase") to Asomtavruli ("uppercase") is invalid (and lossy for some letters!); the inverse conversion is also invalid (but usally not lossy in that direction, so page titles in Georgian should *not* have their first Mkhedruli letter "uppercased" to (Aso)mtavruli, but rather have their (Aso)mtavruli initial "lowercased" to Mkhedruli. This is not what Mediawiki does because it does not use the Georgian casing rules and uses simpler casing rules (that have bugs in various languages, notably in Turkic languages for its behavior with dotted vs. dotless I or J, also in Germanic, Central European and Greek language for the initial/medial/final behavior of S or Sigma and its capitalisation forms or ligatures)