Raise and lower - which is harder? It's not a simple question of which is easier. They each have different things to go wrong. When lowering you are going 'downhill' but you are going from a slow stable rhythm with the balance point on hand if needed into a faster, less stable and mpre crowded rhythm. When raising you are going uphill but the further you go the more open (and familiar) the rhythm.
The seeds of a bad rise are sown with a bad start, failure to establish a stable two stroke rhythm early on. Typically the bells start too spaced out (and take too long to start) so there's an extended period with hand and backstrokes overlapping. Add in any unsteadiness and no one can hear whether they are right or wrong so different bells try to 'correct' in different directions. The whole thing is a mess until the bells are much higher and manage to sort themselves out.
This can be avoided if the Treble rises briskly to start with, which (a) gets quickly to a speed where the Tenor can strike and (b) pushes the other bells together leaving space for the second stroke to come in so everyone can hear what's happening. Once the Tenor is striking on both strokes, the Treble sticks to its tail and goes up at the Tenor's speed but before that it helps if the Treble mantally puts in the Tenor's backstroke so mthat when it emerges everything fits.
I just looked back to see what I said in 'Raising & Lowering in Peal' (is it really 35 years since I wrote it?) You might like to haqve a look. Feel free to copy anything you find useful.