Not exactly hugelkultur, but I've just demolished some internal walls. They are thin european style brick with lime plaster on them.

i want to build a herb spiral and was thinking of using the bricks as infill and to build some height.

It's only terractta brick and lime plaster and as lime is sometimes added to soil for ph, i can't see it doing much harm. Any advice would be welcome!

If those walls have been sitting around for a long time, the plaster is no longer 'lime', but it has now become 'limestone', i.e., the CaO has picked up CO2 from the air to become CaCO3. Nothing wrong with limestone in your planting beds, I wish I had more around here to throw into mine.

If you're sure that the walls contained only old-fashioned lime plaster it shouldn't be a problem, however in a lot of old houses, lime plaster has been over-plastered with modern gypsum based plasters and I wouldn't put those in a veg or herb bed.

If your soil (or water) already has a high pH, you probably don't want to use it as fill. Otherwise it should be o.k.

For example, my water has a pH of 9.2 (soil is a little less) so I don't want to further exaccerbate the issue with lime, limestone, etc.