Yes they are bugged. Someone has mixed the references to the map texture file. This is because for example the game is trying to load map faf_coop_havens_invasion located in Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps folder. However someone named it faf_coop_havens_invasion.v0006. The additional version string at the end is causing path not found when trying to load the screen. A simple fix is just to do the following below to get your mission working.
Step 1.
Go to the path your Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps folder.
Step 2.
Find the mission you want to play ex,(Blockade, Golden Crystals, Tha Atha Aez).
You will see the map folders here in folders named something like FAF_Coop_Operation_Golden_Crystals.v0003.
(If you don't see the map file it will be created on first launch of the mission so just launch the mission once to generate this file.)
Step 3.
Copy the map folder for mission you want to play for example copy folder FAF_Coop_Operation_Golden_Crystals.v0003 and paste it in the same location.
Then rename it FAF_Coop_Operation_Golden_Crystals without the .v0003 at the end.
Step 4.
Launch your game and enjoy.

The game is looking to load the map files without that v000X numbered string at the end. Someone messed up by saving the version at the end of the map file strings and the game is calling the map files without the random versions. This fix works for all of the seraphim and coalition missions.
So
FAF_Coop_Operation_Golden_Crystals.v0003
FAF_Coop_Operation_Blockade.v0004
faf_coop_operation_tha_atha_aez.v0014
folders become
FAF_Coop_Operation_Golden_Crystals
FAF_Coop_Operation_Blockade
faf_coop_operation_tha_atha_aez
Then your game will load the map textures. Make sure you keep the original map folders in the Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps.
I'm not sure what happens if you remove them. So its safer for now just to duplicate the folder with the correct name.

For anyone still dealing with the minecraft blocks for T1 Walls. I've created a mod called 'T1 Walls (Vanilla)' and released it on the FAF client.
This mod will restore the original T1 Wall sections into your game for immersion purposes.

This is a work around for now, I'm sure the April fools blocks will be removed at some point.

For anyone still dealing with the minecraft blocks for T1 Walls. I've created a mod called 'T1 Walls (Vanilla)' and released it on the FAF client.
This mod will restore the original T1 Wall sections into your game for immersion purposes.

This is a work around for now, I'm sure the April fools blocks will be removed at some point.

@IndexLibrorum Just wanted to play simple co-op after work. Instead spent hours trying to fix, gave up and just went to other games... Can this be removed now its April 3rd? Talking on the Newbie chat, others also spent hours trying to figure out what mods they thought broke their game. Any way to disable this in the future? Kind of personal modded setup going and its immersion breaking random minecraft block nonconsensual added to our game. Really don't want random things injected into our builds. If not just have to block FAF from internet access to stop random objects being swapped in. At least a random dev didn't go rouge and start installing things on our system which is one of the concerns originally. Probably should be a news update celebrating April 1st instead a ghost update forced down to clients. Even AI was fooled an sure this was not an April 1st joke an the game needed to be reinstalled for broken textures.

Yes they are bugged. Someone has mixed the references to the map texture file. This is because for example the game is trying to load map faf_coop_havens_invasion located in Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps folder. However someone named it faf_coop_havens_invasion.v0006. The additional version string at the end is causing path not found when trying to load the screen. A simple fix is just to do the following below to get your mission working.
Step 1.
Go to the path your Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps folder.
Step 2.
Find the mission you want to play ex,(Blockade, Golden Crystals, Tha Atha Aez).
You will see the map folders here in folders named something like FAF_Coop_Operation_Golden_Crystals.v0003.
(If you don't see the map file it will be created on first launch of the mission so just launch the mission once to generate this file.)
Step 3.
Copy the map folder for mission you want to play for example copy folder FAF_Coop_Operation_Golden_Crystals.v0003 and paste it in the same location.
Then rename it FAF_Coop_Operation_Golden_Crystals without the .v0003 at the end.
Step 4.
Launch your game and enjoy.

The game is looking to load the map files without that v000X numbered string at the end. Someone messed up by saving the version at the end of the map file strings and the game is calling the map files without the random versions. This fix works for all of the seraphim and coalition missions.
So
FAF_Coop_Operation_Golden_Crystals.v0003
FAF_Coop_Operation_Blockade.v0004
faf_coop_operation_tha_atha_aez.v0014
folders become
FAF_Coop_Operation_Golden_Crystals
FAF_Coop_Operation_Blockade
faf_coop_operation_tha_atha_aez
Then your game will load the map textures. Make sure you keep the original map folders in the Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\maps.
I'm not sure what happens if you remove them. So its safer for now just to duplicate the folder with the correct name.