Not sure about the fact you wish to mix both very different tv series. smudger9 somewhat did that on his (sadly unfinished) movie-series, but it only was dialogue excerpts, not footage. So… good luck !
They aren’t mixed so much as we start with one and end with the other. Visually yes it’s a bit weird, but it plays fine, especially since Obi-wan is the same throughout. Since they originally were planning on both series being in continuity with each other we never get a strong Grievous intro in TCW and having Obi-wan vouch for Anakin before the council is really important imo.