際に/際/際は => occasion, time N2
中 => While (Lasting) N3
Continuous
[際「さい」]して/に([際「さい」]し)/に[際「さい」]しての => At the time of A (which starts now).. N2
Time, Situation
途中で/途中に => on the way; in the middle of ~ N4
中 => During the period (Term) N3
Time
に際して => on the occasion of; at the time of ~ N2
を中心に => focused on; centered on~ N2
最中に => while; during; in the middle of ~ N3
途中 (は) => on the way; in the middle of ~ N3
Halfway
中 => Throughout, all over, during the course of N5
Time
(の中)で~が一番~です => out of this group, [A] is best N5
[最中「さいちゅう」] => In the middle of A N3
Time, Situation