For example, when you lack a single piece it should say:
On the other hand, when you lack multiple pieces, it says:A una entidad le falta el material para la construcción
If we look at it, the variable depends on if we need ONE or MULTIPLE items so it changes between "A una entidad" (una = one) or "a 5 entidades" where 5 is an example number.A (number) entidades les faltan el material para la construcción
However, ingame we see this:
So I assume the variable is bugged and somehow shows as plain text.A __plural_for_parameter_1_{1=una entidad le falta|rest=1 entidades le faltan} el material para la construccion.
Proof: https://i.imgur.com/KvpB1l9.png