Calling ‘cross’ a mere metonymy for Christ breaks where the hymn opposes and distinguishes the cross from Christ
Modern metonymy (‘cross’ = Christ) cannot rescue texts that oppose, distinguish, and praise the cross by bodily contact apart from Christ.
Latin
XXIV. Vim autem manifestam verbis ipsis faciunt, qui, ut absurdum istud vitent, hodie volunt crucem, per Metonymiam quandam, pro Christo ipso accipi in ejusmodi precationibus. Nam quae loquendi leges patiuntur, ut crux pro Christo crucifixo sumatur, iis ipsis in locis ubi Christo opponitur, & a Christo contradistinguitur, & celebratur tanquam contactu corporis Christi nobilitata?