But in fact, I think one does not need to shift the Timing_translator to the staff context at all: It should suffice to use \scaleDurations and a manual tweak of the displayed time signature for one staff.
That was easier than I had expected: \version "2.23.0" musicOneSizeFitsAll = \relative c' { \time 4/8 c'8 d16 c b8 c \tuplet 3/2 { d8 f e } d4( c2) } \score { << \new Staff { \set Staff.timeSignatureFraction = 4/4 \scaleDurations 1/2 \shiftDurations -1 0 \musicOneSizeFitsAll } \new Staff \musicOneSizeFitsAll >> } Lukas