Lovely bows! The ERC is a smasher.
I'm gonna be really annoying now, but there is something worth bearing in mind when making replicas of the MR bows (it's 90% of what my customers request so I've got a love/hate relationship with them!) which you've brought up, regarding the surprisingly elliptical tiller.
Many of the MR bows are awful - badly made, overly rushed and clearly considered back then as a tool made to satisfy an order list, not long-term personal weapons. I have no idea if this short one is a good one or a bad one (they're pretty distinguishable in person, I'll do some digging and make sure I locate it next time I'm there for you) but if it's a dodgy one the chances are the tiller wasn't important at all. I've got my own theories on how they were made, but essentially there's a good chance the original bow was never even on a tiller. Also, loads of the bows have deep, deliberate heat treating marks in consistent areas of the belly - lots in the handle/fade areas, and also about 8" from the tips. This to me suggests that they were tempered over charcoal to stiffen up the weak areas that would otherwise result in overly elliptical tillers, if not hinges.
Unless you've got the bow in front of you, there's no way of knowing whether the one you're copying has these or not. I'd be willing to bet it does, which would mean the original bow wasn't as elliptical as yours. The nice thing about being able to study the ones you're copying in person is that you can see those heat marks and copy them, or leave slightly more wood there to give a similar strength to the belly. I've not got WoW to hand, but is the original a galleon section, or more D shaped? Thats another deciding factor, as the latter would give more compressive resistance midlimb to tips, and you wouldn't know just by the measurements as you only get width and depth from the book (and they're usually slightly out, too!)
That then begs the question - do you go into bowyer mode, and take what is perhaps an overly-elliptical tiller and tweak it slightly to bring it round more (especially on such a short bow) or do you stick with an "exact" replica regardless your instincts as a bowyer, possibly to the detriment of the bow's longevity?