I'll give Maki a shot whenever I'm able to upgrade my gears!
I immediately remembered that there are different paradigms on making songs for actual singers and for voicesynths. If you want to make a song for actual singers, you have to take care of their vocal cord by choosing the range suitable for them (unless if they want to take challenges). In terms of making songs for voicesynths, albeit the range "recommended" by the companies, producers went ahead and broke those "limits" because "the broader the range, the better!" (even though this is not always the case, this paradigm is indeed present in the scene.)"It must be so hard for Uneko to sing it live, but still came out so great!"
"It's too high"
"What a nice performance by a mother and her daughter! Though this song can't really be sung by an average person "
"Due to the original key was too high, Uneko immediately went back to the stage to beat her daughter"
"Maybe she should beat KBShinya instead"