I took a closer look and I believe the issue lies with R itself.
It seems that the title in the DESCRIPTION file is re-encoded when the package is installed -- for example, try executing
dcf <- read.dcf(system.file("DESCRIPTION", package = "<yourPackage>"), all = TRUE)
dcf[["Title"]]
In my case, I see the title erroneously re-encoded when there are multi-byte characters. I originally had the title field as:
Title: Buongiòrno!
but after installation, I see when attempting to read the DESCRIPTION file:
> dcf[["Title"]]
[1] "BuongiC2rno!"
and this is even when I declare Encoding: UTF-8 in the DESCRIPTION file.