The specimens from Cuba were not examined by Steadman and Takano:
"The specimens of Gallinago new sp. from Cuba (3 humeri, 1 ulna) are from Cueva El Abrón in Pinar del Río Province, and Cueva de Humboldt and Cueva del Salón in Sancti Spíritus Province (Suárez, 2004). We did not examine this material directly although we evaluated the osteological characters provided by Suárez (2004)."
The holotype is a complete humerus, identical (parts of) humeri were found on the Cayman Islands.
The holotype humerus bears the name. the rest are paratypes and refered material, so I would not conclude they are all the same species although I think it is likely. Ir happens sometimes that some referred material of a species or even some type material or paratype material is used to erect a new species.
So was the holotype of Pseudoseisuropsis wintu Stefanini, Gómez et Tambussi, 2016 a former paratype of Pseudoseisuropsis nehuen Noriega, 1991.