We are struggling with exactly the same issue.
Getting the two grading systems to calculate the same grade was next to impossible, because of differently weighted assignments and categories. We also founf the need for the teacher to manage assignments in both systems to be silly.
Kimono is supposed to allow for term level scores via the One Roster Passback.
I haven't been able to get an answer from anyone as to how to enable this. Infinite Campus answered by stating that the only preferred partner that they allow final grade pass back with is Schoology.
We have turned off the grade pass back for now and written a sql program that imports the current grade from canvas.
This script updates the in progress grade each night with the current % score in canvas.
To make this work we had to remove grade book access in infinite campus, and now have teachers use the "post grades" tab in IC to manually enter the in-progress grade that we import.