Hi there I am also founding a guild, very similar idea to yours, I am fairly competent builder. I ran a minecraft server (pokemon based) and me and my gf have only played boundless for about 4 weeks now but have managed to start a castle project taking roughly two weeks (on and off) independently. My gf is a pixel artist and has a knack for unique or difficult shapes and I enjoy toying with colour composition, scale, layout, decorative touches, concepts and (more importantly in this game) chisel work.
Example of our recent work on boundless:
Example of previous work on minecraft:
We would love to work with you either as a guild member or maybe an alliance depending what region your server is based. Even though I have not worked with that software before i am sure I would be able to get the hang of it quick enough. My only concern with the program is that it obviously does not have the chiselled block options that boundless currently has and will soon increase dramatically.
p.s love the designs 
awesome!