Solemen

CF is weird on that but I don't have any experience with Valk to give a reason why it doesn't work, sorry. I played Bang and we have a combo path involving a float in between a midscreen combo and it does not work on any of the 5A/2A starters but would work on a 5B/2B starter. In my experience of CF, minor changes to certain combo path might make them invalid at some point. You are rather forced to either omit a move or try a new string but in the end, it is something you have to remember and it is kinda of a pain to manage. Sorry if this was not the answer you were looking for.

I think they made short starter combo almost the same length as normal starter but the frame in between hits are noticeably shorter for short starters. So the more hits you add, the more likely the combo will drop somewhere which requires more frames in between moves. This applies also on air starters so careful on that as well. CT doesn't have bonus proration by the way and has a bad P2 value unless you partially charge it (max version gives the same P2 value as partial which is 100). Should also note that some overhead starters have become short starters too.