I place sea lanterns up to 2 blocks thick around a zombie spawner and they are useless for the light lever and seem to not block spawning like a normal solid block would either. The second thing may be normal as the sea lantern has solid and transparent qualities.

I tested this extensively. The sea lantern light seems to work to prevent other/normal mobs from spawning but it's light seems to have no effect on spawners (zombie) Torches shut down the spawning by increasing the light level as they normally would. A single layer of sea lanterns surrounding the spawner with cobblestone at the layer below the spawner and lanterns does nothing perceivable to reduce or prevent spawning.

I have searched for the issue under "spawner" and "mob spawner" and found nothing.

Does the code for spawners treat light from sea lanterns differently?

*side note:

Sea lanterns seem to lag the crap out of my NOTE 4 running MCPE. Torches and various other light sources seem fine. It is weird and makes them useless to use if I am using my phone. I am not familiar enough with the mechanics, lighting graphical rendering details, GPU load handling, chipset influences,....etc.... to know if it is a device specific issue or if it is just a huge difference in processing demand and capacity between my computer and phone but both are high performance and capable.

When I made a room with Emerald blocks and sea lanterns it was completely unplayable! it was like a graphics benchmark test or something! Totally unplayable.

I know it is a separate issue I just thought it was worth mentioning because the issue this is about is regarding the lighting mechanics of sea lanterns and maybe there is significance to it.