Improve mx transitions effects and possibilities

I am using the mx transitions ( elastic. Strong) to give effect to many small mcs.
It is ok but I meet 2 things that I would like to ameliorate :
1 - Even if I set up the main timeline at 30 fr/scds and give a speed of 0.2 for the duration in my code, when I rollover on my mcs, some of them hardly react to my mouse when I test my animation by passing my mouse on all of the ( with delay or nor at all).Why such an imprecision, is there a better way to have them all reacting well and fast.
2 - The elastic effect starts from the top left corner but I want it to start from the center. I tried with setting the registration point of my mcs to the center, but it does not change anything…How can I solve this ?
Thank you for your advices,:jail: