I'm heading to bed so I'm just going to rapid-fire in one giant paragraph:
Touhou Original are probably fine if they're not listed in the touhou list already. Pixiv Fantasia stuff is kinda in a bizarre situation so either way is probably fine, maybe just group them under a pixiv fantasia header. Okino could just as easily be a copyright as a character there seems to be more than one character design at least. Ancerl is tagged Creation I imagine Merci is the same. I tried to figure out what was going on with mygrimoire once but gave up. Qualifiers for original characters should be the original character unless we cannot figure out who created it then character is better than nothing.