It quite likely is a bit more of a problem with ponies. Here's the standard dwarf cull_symbol list from entity_default:
[CULL_SYMBOL:ALL:DOMESTIC]
[CULL_SYMBOL:ALL:SUBORDINATE]
[CULL_SYMBOL:ALL:EVIL]
[CULL_SYMBOL:ALL:UNTOWARD]
[CULL_SYMBOL:ALL:FLOWERY]
[CULL_SYMBOL:ALL:NEGATIVE]
[CULL_SYMBOL:ALL:UGLY]
[CULL_SYMBOL:ALL:NEGATOR]
The ALL bit means they won't name wars or bridges or stuff from those pools, either. Here's the standard earth/peg/unicorn cull list from entity_pony:
[CULL_SYMBOL:ALL:TRADE]
[CULL_SYMBOL:ALL:TRAVEL]
[CULL_SYMBOL:ALL:ORDER]
[CULL_SYMBOL:ALL:DARKNESS]
[CULL_SYMBOL:ALL:BALANCE]
[CULL_SYMBOL:ALL:BOUNDARY]
[CULL_SYMBOL:ALL:RESTRAIN]
[CULL_SYMBOL:ALL:AQUATIC]
[CULL_SYMBOL:ALL:SUBORDINATE]
[CULL_SYMBOL:ALL:NEGATIVE]
[CULL_SYMBOL:ALL:UGLY]
[CULL_SYMBOL:ALL:DEATH]
[CULL_SYMBOL:ALL:OLD]
[CULL_SYMBOL:ALL:VIOLENT]
[CULL_SYMBOL:ALL:EVIL]
[CULL_SYMBOL:ALL:NEGATOR]
[CULL_SYMBOL:ALL:PRIMITIVE]
Besides the five I mentioned, they all seem a little unpony. Fixing that is as easy as deleting the entries you don't want culled, though. Looking at it, I seem to have forgotten to customise rainbow and cave ponies, too. I think I'll let rainbow ponies have untoward names to represent the diomedians heritage, that way we get awesome names like Canyon IncestBlossom.
But really, the easy way to solve this would be to get an expanded vocab and symbols mod and ask if we can steal use it with credit given, so we can still limit the pools for flavour, but also have plenty of variety.