data <- structure(list(text = c("blabla HUGGING_FACE PARTY_POPPER", "bla FACE_WITH_TEARS_OF_JOY bla FACE_WITH_TEARS_OF_JOY", "PARTY_POPPER")), class = "data.frame", row.names = c(NA, -3L))
emojis <- structure(list(name = c("FACE_WITH_TEARS_OF_JOY", "HUGGING_FACE", 
                                  "PARTY_POPPER"), emoji = c("\U0001f602", "\U0001f917", "\U0001f389"
                                  )), class = "data.frame", row.names = c(NA, -3L))
 
library(stringr)
stringr::str_replace_all(data$text, setNames(emojis$emoji, emojis$name))

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