Currently not. It maybe something to think about more long term though. I've never actually developed any Android apps before, but funnily enough I did actually do my first tutorial using Xamarin in Visual Studio last week. It's something I think I'd like to do, but don't have the experience to just yet.
In the meantime, I actually use, and can recommend, IFTTT (If This Then That) for Android. There is a recepie to scrape the best wallpapers from /r/wallpapers and apply them and it works really well. Can't say I've ever had repeats of them either. :)
As long as it's still broken, I find another app doing the same > RedPapper
UI is way more minimalist, there's less features and a very annoying pop-up suggesting basic subs, but it works
/data/system/users/0/
it's not a jpg file, it doesn't have a format. I'm not familiar with tasker but I hope it's able to move every new wallpaper, rename it and add an extension to it..
if not, I recommend using this App.
Theres a great android app which I use called Muzei which changes your wallpaper dependent on selected sources, one of which can be reddit through use of this.
Install Muzei first then the reddit source, launch muzei and select the source, and customize the reddit source for the subreddits you're after.
Hope this helps.