I don't understand H-Roa's gameplay, so I can't tell you what are his best attacks to use on neutral game (and follow it up with a combo), but it's not 2A. 2A is a very important attack because you can whiff cancel with it, so it's not good to waste it so early unless it's his fastest attack and you need that speed to punish something or attack before your opponent, I don't actually know his framedata. I know 5B, 2B and 5C are good, but I don't understand his gameplay, so I can't tell you which to use.
I suggest you to create your own sequence of buttons. For the starter, you need something a little fast, with good range, priority and that you can confirm into a combo easily. For the second hit, something that combo with the first is good, it will give you more time to confirm your combo. For the attacks in the middle, you'll probably want attacks that move you forward, so you can continue your pressure. If you need any reference of what moves to use, you can always watch top Roa players. I will give you an unfair advantage if you watch carefully and put it to practice.