It already is on our radar. We noticed that if the app's Pro version isn't activated when the backup file is restored, the aliases aren't either.
Thank you for your reply and I regret it took me so long to get back to this.
I confess when I encountered the problem, I immediately set about re-creating my aliases and their really-too-complicated signature blocks. Everything's all nice and set up on my phone, now. And I feel very hesitant to put your workaround to the test at this point. Such is our lives, I suppose, when we rely so much on our phones that we cannot risk unsettling them, even for the good of the developer community on which we rely.
I cannot recall if, when I first encountered this problem, I had already activated my Pro version. I think I would have, but I cannot say with any certainty.
I have a rather lofty goal with respect to email signature blocks: As much as possible, I strive to make sure there are few difference, if any, between the graphics and embedded links that I can achieve with my desktop email application, and those I can get from AquaMail. For the most part, AquaMail delivers on this goal. I'm not willing to look at another mail client for my phone, if it doesn't deal with aliases - and their unique signatures - as well as AquaMail.