Your right this is definetly a chance for Tsukune to get stronger.
Your also right that Akasha didn't tell Akua that, but, it has something to do with getting Moka and is about Moka's and Akasha's health, its not surprising that Akua did that, the Wong family is the Miu families rival, as we should all know.
However, being a ruthless assassin that is to be expected, even if Akua is to get Moka in order to complete Akasha's task that she gave her, either way, this all shows that the final battle is definetly gonna be with Alucard.
Touhou Fuhai has also figured out what Akasha whispered to Akua, or is trying to figure out what it was, though he didn't expect it would lead to his family being harmed, though Akasha most definetly didn't tell Akua to do that, Akua did it because it was her mission to retrieve Moka, we know that Akasha is one of the good guys, so we know that whatever Akasha told Akua is good, for the safety of Moka herself, besides im not worried that Moka is with Akua, Omote-Moka is with her as well.
But, this manga and its plot twists, are great, things are beginning to get real interesting, how exciting.
I think it would be so cool if they asked Tsukune to join Fairy Tale in order to get to Moka, a good guy pretending to be a bad guy, thats classic, of course, since the plot twists in this series are so unpredictable i wouldn't be surprised if something like that happened.