Analysis of information sources in references of the Wikipedia article "Spanish phonology" in English language version.
Many studies have shown that within the last 70 to 80 years, there has been a strong transition towards the voiceless [ʃ] in both Argentina and Uruguay, with Argentina having completed the change by 2004 and Uruguay following only recently [...]
The distribution of nasals, however, is somewhat deficient in Spanish. In word-final position only the alveolar nasal is present. So borrowings that end in /ɲ/ or /m/ are generally adopted into Spanish with a final n, e.g. Adam -> Adán, champagne -> champán.