- The opening paragraph or Protocol
The official translation reads "It is truly right and just . . . . at this time above all to laud you yet more gloriously, when Christ our Passover has been sacrificed'. This is surprising, since 'when . . . has' in constructions like this usually refers to future events, for example 'when Richard has opened the door, I shall leave'. The Paschal Preface refers to an event not in the future but in the past, namely the death of Christ, so that 'when Christ our Passover was sacrificed' would be more idiomatic.
But there is another point to be considered. In the background is 1 Cor 5, 7-8: 'Christ our Passover has been sacrificed for us: let us therefore keep the feast'. Here, the connection between Christ's sacrifice and our liturgy is causal, not temporal. We are not merely marking the anniversary of Christ's death but celebrating its enduring power.
The revisers may have been following the classical rule, according to which cum with a subjunctive is causal ('because') and with an indicative is temporal ('when'). But in later Latin this pattern lapses, and cum with indicative, as here, can mean 'because'. So I would argue that this clause would be better translated 'because Christ our Passover has been sacrificed'.
- The final paragraph or Eschatocol
Concern has been expressed concerning the word 'even' in 'and even the heavenly powers . . . sing together . . . the hymn of your glory'. Why should we be surprised that the heavenly powers sing to glorify God? Is that not their principal activity?
The revisers may have been misled by the words sed et in the original. The Latin word sed is an adversative or contrastive particle, regularly translated 'but'. But when coupled with et, sed loses its adversative or contrastive force: sed et means simply 'and also'.
Sed et recurs often in the Missal, and this erroneous translation is repeated in several places, but not in all. For instance, in the Roman Canon sed et beati Ioseph is correctly rendered 'and of blessed Joseph', not 'and even of blessed Joseph'!