Some relatively big changes to the customization system are coming in 1.6 -- which, in short, means that a lot of old mods will no longer work until they are updated. Mods that do not involve changes to any XML files (i.e. the Dakka Improvement Project) will continue to function as normal, but anything that does will break with the new patch.
I am working on fixes for mods affected by this change, along with an update to the Customization Guide (as that has changed as well). Once those are done, I will post an update. Thank you for your patience.
UPDATE (13. August): The majority of my mods on the WGMods hub have been updated and are now available to download. Furthermore, the customization guide has been updated with the new XML file and format. Everything else is still in the process of being updated.