OK, I discovered that I can build when I revert the commit "update to gulp 4" in my local branch. I especially looked at the pieces, as this is where we had most merge conflicts. (And unresolvable merge conflicts, as these were binary files.) I checked Gigachess II, and it looked OK both in 3D and 2D. It uses the new Crowned Bishop in both cases. So I suppose your games are all OK. I think it just kept the fairy-sprites file from the master branch when it could not merge, but you had already adapted that to both of our needs before you merged with master.
Like you noticed, the old 3D Crowned Rook seems to have disappeared. The old 2D sprite still displays, however. (But for mysterious reasons Chu Shogi displays a Small Rook for that!?) The mesh file for my Crowned Bishop was called tiara.js, and it seems to have survived. I will rename it to fr-saint, and modify my variants to use it. (They now all use the new Crowned Bishop.) Most of my variants used a scaled version of the old Crowned Rook, which I had called fr-proper-crowned-rook, so I think there is no problem to make the two versions coexist. It is just that the mesh file for this proper-crowned-rook seems to have disappeared during the merge, so it cannot display. But it should be easy to get it back.
We probably should confer to decide which pieces we want to keep, and under what name. As far of 2D images I am sorely missing an image for the diagonal Cannon (fr-cannon2). In 3D these Cannons look very different, and there are games where I use both of them. But they use the same fairy-sprite. Now that you added so many new pieces, I will probably modify some of my games to use these. (E.g. the Wolf is of course ideal for Werewolf Chess.)
What I would also like to have is winged versions of the Q, R and B. I will see if I can fabricate something. (But it is not easy to create new 3D pieces with gedit as only tool...)
OK, I discovered that I can build when I revert the commit "update to gulp 4" in my local branch. I especially looked at the pieces, as this is where we had most merge conflicts. (And unresolvable merge conflicts, as these were binary files.) I checked Gigachess II, and it looked OK both in 3D and 2D. It uses the new Crowned Bishop in both cases. So I suppose your games are all OK. I think it just kept the fairy-sprites file from the master branch when it could not merge, but you had already adapted that to both of our needs before you merged with master.
Like you noticed, the old 3D Crowned Rook seems to have disappeared. The old 2D sprite still displays, however. (But for mysterious reasons Chu Shogi displays a Small Rook for that!?) The mesh file for my Crowned Bishop was called tiara.js, and it seems to have survived. I will rename it to fr-saint, and modify my variants to use it. (They now all use the new Crowned Bishop.) Most of my variants used a scaled version of the old Crowned Rook, which I had called fr-proper-crowned-rook, so I think there is no problem to make the two versions coexist. It is just that the mesh file for this proper-crowned-rook seems to have disappeared during the merge, so it cannot display. But it should be easy to get it back.
We probably should confer to decide which pieces we want to keep, and under what name. As far of 2D images I am sorely missing an image for the diagonal Cannon (fr-cannon2). In 3D these Cannons look very different, and there are games where I use both of them. But they use the same fairy-sprite. Now that you added so many new pieces, I will probably modify some of my games to use these. (E.g. the Wolf is of course ideal for Werewolf Chess.)
What I would also like to have is winged versions of the Q, R and B. I will see if I can fabricate something. (But it is not easy to create new 3D pieces with gedit as only tool...)