I'm not sure to be honest if it is suitable to let anyone edit your document. if it where me I wouldn't feel comfortable doing that. It might be good though if you had a trusted someone who could help (maybe someone with a large collection) who would be able to add ponies for you.
It might be useful to add images of how you measure the ponies manes and tails? That way people know how to measure in order to be able to use your information correctly
The cm/inches thing is complicated. I'm in the UK and use both cm and inches, I think the UK is supposed to be all metric (cm) but some places never made the switch (even though they were supposed to).
Having all the nirvana ponies measured in cm and the standard issue ponies measured in inches doesn't quite make sense to me. Not all nirvana ponies are European and of course Europe did get HK and China made ponies. Most websites list pony information based on a US centric idea of the releases, and nirvana ponies, EU ponies and elsewhere ponies (Africa and Australasia) do not fit into the US release pattern. Plus we still do not fully understand the releases/waves of ponies in some countries.
I think being consistent in how you measure and what measurement unit you use is the most important thing. We have rulers and measuring tapes, I think most people can work it out or convert measurements
It is your project and you should do what you feel comfortable with
Nirvana stuff is a ton of work (trust me, I should know) and there is certainly enough to keep you going just based on the US centric releases
Love pkw xxx