Yeah, when converting Lego made structure to Blockland, you have to be wary of size.
I tried creating a Castle from which I had instructions for, and Blockheads don't fit in properly.
Where a Blockhead requires approximately 3-bricks width to stand, a Lego Minifig only requires two, when used in most builds. So, following exact instruction, will make your builds slightly too small to maneuvre in.
Anyway, those aren't that bad. The main problem I have with converting Lego-Blockland, is that Lego has such a wide range of bricks. By which I mean bricks used for Hydraulics, pegs, large rounds, and many others. They also get bricks to face in different dirrections to the basic 'N-E-S-W'directions. It's just impossible to convert entirely. You can get around a lot of stuff, with a bit of intellegience, but, it's still quite impossible to make most large builds to their full extent.