Languages with few entries, but with online sources that could be used to fix that:

Entries Language Source
338 Tetelcingo Nahuatl Template:R:Brewer & Brewer 1971
236 Mecayapan Nahuatl Template:R:Wolgemuth et al. 2002
163 Purepecha Template:R:Lathrop 2007
155 Highland Popoluca Template:R:Elson & Gutiérrez 1999
142 San Pedro Amuzgos Amuzgo Template:R:Stewart et al. 2000
135 Tzotzil multiple
128 Southeastern Tepehuan Template:R:Willett et al. 2016
120 Mayo Template:R:Collard & Collard 1984
105 San Juan Atzingo Popoloca Template:R:Austin et al. 1995
100 Kaqchikel Template:R:Ruyán Canú & Coyote Tum 1991
100 Mezquital Otomi Template:R:Hernández Cruz & Victoria Torquemada 2010
100 Northern Puebla Nahuatl Template:R:Brockway et al. 2018
100 Rayón Zoque Template:R:Harrison et al. 1984
100 Rotokas Template:R:Firchow et al. 1973
100 Yosondúa Mixtec Template:R:Farris et al. 2012
100 Zoogocho Zapotec Template:R:Long & Cruz 2000
88 Central Tarahumara Template:R:Hilton & Shoemaker 2016
58 Magdalena Peñasco Mixtec Template:R:Aguilar et al. 2017
55 Cora Template:R:McMahon & McMahon 1959
54 Northern Tepehuan Template:R:Bascom & Molina 1998
51 Isthmus Zapotec Template:R:Pickett et al. 2013
50 Alcozauca Mixtec Template:R:Stark et al. 2013
50 Highland Puebla Nahuatl Template:R:Key & Key 1953
50 Huichol Template:R:McIntosh & Grimes 1996
50 Jakaltek Template:R:Church & Church 1955
50 San Juan Colorado Mixtec Template:R:Stark et al. 1986
49 Tataltepec Chatino Template:R:Pride & Pride 1970
43 Francisco León Zoque Template:R:Engel, Engel & Mateo 1987
37 Isthmus Mixe Template:R:Dieterman et al. 2018
37 San Juan Guelavía Zapotec Template:R:López, Jones & Jones 2012
24 Chicahuaxtla Triqui Template:R:Good 1979
20 San Miguel el Grande Mixtec Template:R:Dyk & Stoudt 1973
19 Coatlán Mixe Template:R:Hoogshagen & Hoogshagen 1997
18 Yatzachi Zapotec Template:R:Butler 2000
16 Western Highland Chatino Template:R:Pride & Pride 2010
15 Oluta Popoluca Template:R:Clark 1981
15 Sayula Popoluca Template:R:Clark 1995
14 Guerrero Nahuatl Template:R:Aburto & Mason 2005
14 Highland Totonac Template:R:Aschmann 1983
14 Lacandon Template:R:Baer et al. 2018
13 Tezoatlán Mixtec Template:R:Williams et al. 2017
10 Chayuco Mixtec Template:R:Pensinger 1974
10 Huave Template:R:Stairs et al. 1981
10 Papantla Totonac Template:R:Aschmann & Aschmann 1973
10 Tanimuca-Retuarã Template:R:Strom & Strom 2019
10 Tlamacazapa Nahuatl Template:R:Aburto & Mason 2005
9 Chiquihuitlán Mazatec Template:R:Jamieson Capen 1996
9 Xicotepec de Juárez Totonac Template:R:Reid & Bishop 1974
8 Copainalá Zoque Template:R:Harrison, Harrison & García 1981
6 Copala Triqui Template:R:Hollenbach 2019
4 Totontepec Mixe Template:R:Schoenhals & Schoenhals 1965