Where no judgments as to merit suffice

"Be pleased, O Lord, with our humble prayers and offerings, and, since we have no merits to plead our cause, come, we pray, to our rescue with the protection of your mercy. Through Christ our Lord".

"Placare, Domine, quæsumus, nostræ precibus humilitatis et hostiis, et, ubi nulla suppetunt suffragia meritorum, tuæ nobis indulgentiæ succurre præsidiis. Per Christum Dominum nostrum".

Be reconciled/appeased, O Lord, we pray, by the prayers and sacrifices of our humility, and, where no pleas/judgments/aids/supports of merits are at hand/in store/suffice, hasten to help us with the garrison/troops [(præsidiis, defenses/protections)] of your indulgence. Through Christ our Lord".

     Prayer over the offerings, Second Sunday of Advent.  That "since" may be too good to be true.  For I see no indication that ubi functions in that way in even the medieval Latin covered by the Dictionary of mediaeval Latin from British sources, let alone the classical.  That phrase should therefore run not "since no votes or backings of merits—i.e. no judgments of merit—suffice," but rather "where no votes or backings of merits—i.e. no judgments as to merit—suffice."  Corpus orationum, in which this appears as no. 4246, citing the Gregorian, the Old Gelasian, and so forth, gives the original word order as follows:

"Placare, Domine, quæsumus, humilitatis nostræ precibus et hostiis, et, ubi nulla suppetunt suffragia meritorum, tuæ nobis indulgentiæ succurre præsidiis."

1973 (very loose):
Lord, we are nothing without you. As you sustain us with your mercy, receive our prayers and offerings.