This can be reproduced with lwjgl3ify 2.0.4 + EFR 2.6.0-beta-1.

EFR calls addExtensibleEnum here, to register ganymedes01.etfuturum.tileentities.TileEntityBanner$EnumBannerPattern. This used to work when the code was added (pre-RFB), but no longer does: the IExtensibleEnum interface doesn't get added, and an EnumBannerPattern was not made extensible crash happens if Botania (+Baubles) is present.

The issue is me.eigenraven.lwjgl3ify.core.Config sees the version of me.eigenraven.lwjgl3ify.rfb.EarlyConfig loaded by LaunchClassLoader, while me.eigenraven.lwjgl3ify.rfb.transformers.ExtensibleEnumTransformer sees the version loaded by RfbSystemClassLoader (I checked this by calling EarlyConfig.class.getClassLoader()). Therefore the transformer doesn't see any enums registered programmatically.