When placing rechiseled blocks, the textures rendered are the texturesheet on every face instead of properly applied. I tried using a custom ressource pack but that didn't help.

BlueMap does not and will not support Rechiseled natively ..
I am working towards making it possible to create addons that add explicit support for mods like Rechiseled, but thats still on the TODO :)

Alright thanks! :) Thanks for the quick answer and thanks for making this mod/plugin I am enjoying it very much ^^