If Player A assign a block, Player B not get the updated texture.
Only if some player update the world near to the block (same chunk) (place a block, break a block, break a plant, etc...) Player B can see the new texture.
Also if the Player B change Render Distance (update Rendering) Player B can see the new texure.
Tested with the latest minecraft forge 1.12.2 version (forge-1.12.2-14.23.5.2847)
If Player A assign a block, Player B not get the updated texture. Only if some player update the world near to the block (same chunk) (place a block, break a block, break a plant, etc...) Player B can see the new texture.
Also if the Player B change Render Distance (update Rendering) Player B can see the new texure.
Tested with the latest minecraft forge 1.12.2 version (forge-1.12.2-14.23.5.2847)
Mods installed:
blockcraftery-1.12.2-1.3.1.jar mysticallib-1.12.2-1.3.7.jar
is this pullrequest: https://github.com/MysticMods/Blockcraftery/pull/43 in the latest build included?