@Bernard-0 has posted a nice AppleScript-based solution—easier than the method here. But i’ll leave this in case it helps Bookends users or those trying RIS export from some other reference manager.
RIS field codes aren’t listed in the Bookends docs (just checked) but helpfully they are on Wikipedia here.
It would appear that RIS doesn’t have a nominated field for the translator (i.e. the person who translated the original work). But in Bookends’s Format Manager, Bookends’ ‘Translator’ field is code ‘u3’
This is Bookends’ RIS export format templates for a Journal:
`TY - JOUR`
$AU - $a
$T1 - $t
$KW - $k
$PY - $d
$JA - $j
$SP - $p-
$VL - $v
$IS - $i
$SN - $u6
$AB - $b
$N1 - $n
$UR - $z
$U1 - $u1
`ER - `¬
Note the $ symbols and back-ticks are Bookends format specific code.
RIS has undefined fields U1 through U5 noting that UI is already in use. By adding a line $U2 - $u3, Bookends drags should include Translator data (if that reference has such information). Thus, note the new ocde in the last but one line:
`TY - JOUR`
$AU - $a
$T1 - $t
$KW - $k
$PY - $d
$JA - $j
$SP - $p-
$VL - $v
$IS - $i
$SN - $u6
$AB - $b
$N1 - $n
$UR - $z
$U1 - $u1
$U2 - $u3
`ER - `¬
Field order doesn’t matter, but the RIS first line must start with TY and the last line with ER. Also, there must be exactly two spaces between a lines opening code and the hyphen, i.e. U2+[two spaces]+hyphen+[space]+etc.
If you undertake this customisation in Bookends, there are four ‘types’ within the format (Journal, Book, etc.) so you should edit all four.
Once data is in Tinderbox, parse the $ReferenceRIS attribute date in the reference’s note for the ‘U2’ field data.