Thanks for sharing your application. It takes guts to be open about this kind of stuff.
One thing I didn't see in the application was what your distribution strategy will be. I understand the collaborative nature of GitHub for Writers, but are there established channels that you could take advantage of to help your customer acquisition. Publishers are one group but perhaps they don't closely manage writers in that way. Perhaps advertising firms or print media might be a way to go. A couple big enterprise customers might be good validation for your business.
A manager can be a mentor regardless of the type of organization. What is important if you want to improve a particular skill set is that the people that are managing you truly understand what it takes to do your job well and can provide feedback on what you are not doing well from a "do-ers" perspective - more of an apprenticeship model.
I have personally found that mentors are great for career advice and resolving questions, but never have enough "skin in the game" to invest their time in my development.
One thing I didn't see in the application was what your distribution strategy will be. I understand the collaborative nature of GitHub for Writers, but are there established channels that you could take advantage of to help your customer acquisition. Publishers are one group but perhaps they don't closely manage writers in that way. Perhaps advertising firms or print media might be a way to go. A couple big enterprise customers might be good validation for your business.