The marked letters should be removed.
C is basically an arbitrary use of K and S.
Can > Kan, Cum > Kum, Center > Senter
J is basically Y
Jack > Yak, Job > Yob.
Also we should stop calling Y as "wuai" instead of it's proper pronunciation "JJJ".
Q is basically a lazy mix of KW.
B and V are literally the same and are mostly used randomly except for a couple of rules.