Both the ray tracing for the fairy light bulbs and the wire result in an "unknown" entity being reported, and information is not shown at all for the fastener block.

To resolve the block not reporting an item, IWailaDataProvider#getWailaStack could be utilized to pass an ItemStack of generic fairy lights, and provide information about currently fastened lights in IWailaDataProvider#getWailaBody

Similarly, IWailaEntityProvider could be utilized to pass custom entity information for the fairy lights entity being raytraced, however I'm sure there is likely a solution without needing the API for you to provide a localized name for your entity that Hwyla can infer.

Mod version: 2.1.2-1.12.x
Hwyla version: 1.8.26-B41_1.12.2
Forge version: 1.12.2-14.23.4.2744