Perhaps:
library(stringi)
library(magrittr)
"foo<U+0161>bar and cra<U+017E>y" %>%
stri_replace_all_regex("<U\+([[:alnum:]]+)>", "\\u$1") %>%
stri_unescape_unicode() %>%
stri_enc_toutf8()
## [1] "foo?bar and cra?y"
may work (I don't need the last conversion on macOS but you may on Windows).
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