"From Middle High German tanzen, ultimately from Old French dancer" according to https://en.wiktionary.org/wiki/%D7%98%D7%90%D6%B7%D7%A0%D7%A6%D7%9F#Yiddish :)
"We seldom dance together" would be correct English, and at least in my dictionary, "seldom" is also given as a translation for "редко". A native speaker might know better whether it should be reported. You could do so anyway though.
Using the progressive "dancing" here doesn't work, as that suggests a fixed time period, while "seldom" and "rarely" refer to the lack of multiple instances.
"We rarely dance with each other" = "мы редко танцуем друг с другом".
People can dance together, but not with each other, for example a collective dance