Why does "merk" mean "meld"? Is it Japanese, Hymmnos, or something else?
According to the EXA_PICO Universe Wiki's Grathmeld article, in the original Japanese, it's グラスメルク, or "Glassmerk"?
Ar tonelico Qoga: Knell of Ar Ciel Original Soundtrack Disc 2: Song 24 is originally titled as Merk~Tilia in English letters, which makes me think it's Hymmnos. A translation is Meld~Tilia.
I haven't seen any "merk" entry in any Hymmnos vocabulary list, so I'm not sure what language "merk" is from.
Although, I suppose it could be a distortion of "make" or something, if it is Hymmnos?