Well, it's really like that.
'Sayumayu' is a Project because it involves a large cast of characters and a global scope of events. However, it's not something I approach with the same dedication I use with, let's say, GOSPEL or Fuujinroku. Those two have a rather encompassing setting and, of course, a full set of power mechanics.
For Sayumayu I come up with techniques on a chara-by-chara basis. For the most iconic characters and techniques I go with the standard strategy followed by shounen manga: technique thematic.
For example, all of Mayuri's techniques are named after Cthulhu Mythos stories. This works both ways: I come up with a spacetime technique and then look for a book with a relatively appropriate name, or I see I name I like and come up with a suitable technique.
In the same way, the different 'Syntheses' of Jutsu Tougou are named after Japanese gods. Sayuri has her Pwetty Beam and its variations. Yurina's and Shaka's are based on Buddhist concepts, kinda like Pain's. Kotonoha's sword techniques are named after the anime episodes. The whole idea behind the Void comes from Exalted. With Karen I use the same funky trick Kishimoto uses with the Kumo shinobi's jutsu, making wordplays of English and kanji. And so on, and so on.
Since I come up with jutsu on a case-by-case basis, I check power levels on a case by case basis: "Ok, so I have this jutsu for Yuriyo. She's a two tails, so how far can I take this technique?"
I would be willing to write short descriptions of the new Jutsu Types. I mean, everybody knows Katon, Raiton and the rest, and you what kinds of things can be done with those five and their combinations (then again, so far my only Katon-using OCs are Setsuna and Sayuri. We can safely assume Setsuna can use all Katon jutsu shown so far in canon, and Sayuri...well...).
However, I guess things like Kakuton, Reiton, Kouton, Kuuton and Juuton deserve a more detailed explanation on what exactly can be done with them.
The Spacetime Jutsu of Time Kitsune have to be dealt with individually. Each jutsu is gamebreaking in its own unique way, after all...which will it more impressive when our heroes and heroines overcome them.