Merami (Now Meramipop- Cosmopolitan) is part of the groups Rd-sounds/ Diao Ye Zong and Kachi Kachi Yama and other groups as colaboration, she also has a RU-vid channel where she uploads covers, some requested by fans, and releases original albums, not related to Touhou. I have no idea about Teto, I only saw that he collaborated with a group but I don't remember the name.
Oh my god you're RIGHT I know that Omoi and FGE have some shared influences, although Omoi lean more into emo/alt-rock but wow it's a little spooky LOL
1:49 keshite onaji de wa nai hiai toko no kokoro wa toozakaru subete no ikeru mono mo kinou no kioku mo ima no watashi mo hitori koko de yume wo miru fukaku ochite yuku shizuka ni yureru yureru fureta koto mo nai yume wo kanata e to yami no kanata e to shizuka ni shizumu shizumu 3:22 iie mitekita no deshou doko ni mo yukenai koraeta mono wa oku e hikari no kage e kagereba satorare satorarereba kageru hikari wa mawaru mawaru kakushigoto wa kogoru obore nagara yuku shizuka ni yureru yureru fureta koto mo nai yami no kanata e to inochi no kanata e to shizuka ni ochiru ochiru
hora yuuhi mo ochikitte soyo kaze ga hada wo kiritsukeru kara negai wo mahou ni komete otsukisama ni koi wo shiyou nee doko kara nandarou ne kaerimichi ga mienaku naru no wa hoshi no chiratsuki mo kowaku omoete ashi ga motsureru no wa hora hito furisae sureba konna ni mabushii yo yume no you itsumademo odottetai yo ne tsukareru koto mo nai yo nee ima dake kangaetai yo itami nante mou wasuretai yo minna zero ni shitekureru mahou ato wa nanimo iwanai yo darenimo shirienai mabushii tokoro e mado wo koete saa oide yo kowagaranai de sugu ni kawareru yo kinou no anata ni wa kaerenai yo keshiki ga maboroshi to mazariyuku aa omoide wa usurete darenimo shirienai mabushii tokoro e mado wo koete saa oide yo kowagaranai de sugu ni kawareru yo mukashi no anata ni wa kaerenai yo kaesanai yo modorenai yo modoritai yo