How naval treaties constrained non-signatory small navies

Did naval treaty limits apply to smaller navies such as those in South America?

Indirectly: foreign builders disclosed export designs, and most small navies lacked the yards to build an over-limit ship themselves.

Treaty powers had to disclose the characteristics of warships ordered for foreign customers. A South American navy could therefore commission a ship abroad, but it could not quietly evade the major powers' limits. Building something larger at home required industrial capacity that these customers generally lacked. The treaty system thus constrained them indirectly through shipbuilding markets and infrastructure rather than only through formal membership.