No so easy job to adapt something for everyone's taste. I don't have TQ on my phone so my opinion will be based on other similar android games and TQIT for PC, and your post above.
1. This is in generally hard task to make to be good for every phone. Depends on phone brand, android version, screen size, user fingers... So when in hurry you miss to hit the button this is something very subjective, but most of players probably have this problem.
2. Maybe additional button can solve this, I saw this problem in other games.
3. Is this the same game behavior like on PC version of the game? I think on PC you need to go with cursor over next target, but what if it focus here weak monster and other tough monster is going to kill player.
4. Sounds like priority target is not set, on PC version when you hold ctrl or shift usual target can be closer monster.
5. This sounds like a game mechanics bug and it should not be hard to be fixed.
6. #1 problem in TQ game is limited bags capacity, but on pc is not hard to teleport and to sell items. On 1 android game I saw auto-picking items and filtering. That game also have hidden shop with chance to get there, but character bag have an option to sell items for 50% less money. Filtered items with low price or bellow quality category are automatically destroyed/sold so player won't bother to go all the time to his inventory. Something like this could improve player experience on android.
All this is just my opinion from my experiences, so this is just my ideas and my point of view. Also as for now unexperienced software tester this is how do I see situation that you presented in this topic.