I know she will be weak, but this is the correct way to balance all champions, especially a problem child. Start weak, assess, small buff, assess, small buff, assess. Rather than start with an over loaded kit and dial back things that are oppressive slowly. Of course the best way to balance is to hit the mark perfectly every time, but that's unrealistic.
For instance: Her healing is a big deal, but she does have hextech. Can she survive till hextech with out the buff so that we can put more damage into Q or a lower cost?
Her shroud can be spotted under tower, will this effect most Akali players as tower dives were always an option not a requirement? Since the re-stealth was increased to allow tower shots an AA to hit her. Do we just reduce the visiblity window and allow all abilities and AA to complete?
These are question they will be asking themselves, the answers will come, but not until she is played live. The PBE is terrible for balancing, live is the only way.