Note that "մեքսիկացի" is for "a Mexican [person]" in Armenian. So it is not attributable to "ետնախորշ" inanimate noun.
The correct Armenian word for "Mexican" in the above context (attributable to "ետնախորշ") will be "մեքսիկական ետնախորշ" or, perhaps, "Մեքսիկայի ետնախորշ" (in a sense of "slums of Mexico") or "մեքսիկացու խրճիթ" (in a sense of a "Mexican's hovel").

Also note that Armenian "ետնախորշ" is rather for a slum (an area built over with hovels), than a single hovel ("խրճիթ").