you really get the feeling THR is trying to reach a target VS (function of time) by setting a given amount of thrust. And this of course, for small changes. If we can’t reach the target altitude by 2min, we get full climb thrust (THR REF) and speed is back on the elevator.
Not ‘back on the elevator’ - it’s always on the elevator in FLCH, regardless of what thrust happens to be set. (Leaving aside whatever might happen now in low speed reversion, which is after my time)