I see, thanks. I think the purposes of our codes are different, for adding a single SE ability, my attempt is ok.

Well, at least it is possible for ERA to store parameters before !!EA and restore after the execution of EA when the modification is just a new SE ability or remove one (which does not affect parameters at all), right?
If this can't be resolved, I believe "all the scriptwriters should unite". We have to restrict the use of EA for stacks, for example, use !!EA only on !?BF and !BM only after !?BF.