In Esperanto, the male pet name suffix, attached to a shortened form of the stem, is ‘ĉj’. Therefore, since ‘grandfather’ in Esperanto is ‘avo’, it seems like ‘grandpa’ ought to be ‘avĉjo’, but Wells gives merely ‘avo’ for ‘grandpa’, and Benson doesn’t include ‘grandpa’ at all. However, ReVo gives ‘avĉjo’, and Vikivortaro seems to agree, giving ‘avĉo’, which presumably is a typo for ‘avĉjo’. (Sonja does not have an entry for ‘grandpa’.) So, my take is that ‘grandpa’ in Esperanto is ‘avĉjo’, and that Benson and Wells simply slipped up on this entry, and Vikivortaro committed a typo on this entry. Do you agree?
Similarly for ‘grandma’: In Esperanto, the female pet name suffix, attached to a shortened form of the stem, is ‘nj’. Therefore, since ‘grandmother’ in Esperanto is ‘avino’, it seems like ‘grandma’ ought to be ‘avnjo’, but Wells gives merely ‘avino’ for ‘grandma’, and Benson doesn’t include ‘grandma’ at all. ReVo, which includes an entry for ‘grandpa’, does not have an entry for ‘grandma’, nor does Sonja have an entry for ‘grandma’. Vikivortaro gives ‘avinjo’ for ‘grandma’, but it seems to me that the ‘pet’ form should be shorter than the regular form. So, my take is that ‘grandma’ in Esperanto is ‘avnjo’, and that Benson, Wells, ReVo and Vikivortaro all slipped up on this entry. Do you agree?