Even apart from these: God would not even have had to create such animals to punish the Egyptians. Good News Translation has “But this was not necessary.”

Men could fall at a single breath may be rendered “you could have wiped out these people with a single breath.”

When pursued by justice and scattered by the breath of thy power: Scattered translates the same word rendered “belch forth” in verse 18; see the comment there. For the first three lines of this verse, another possible model, somewhat closer to the Greek, would be “But this was not necessary. If you were determined to punish sinners just by breathing on them and blowing them to pieces [or, scattering them] with your power, you could wipe them out [or, kill them all] with a single breath.”

But thou hast arranged all things by measure and number and weight: But introduces a long description of what God did instead of punishing the Egyptians in one powerful act; that description continues until 12.2. In some languages it may be necessary to make this clear. Good News Translation unfortunately omits the idea of putting everything is in order (arranged). Some other possible models for this line are “But you didn’t punish them like that. All your works are in perfect order [or, balance], measured, counted, and weighed”; “But … There is order in all your actions; everything is measured, counted, and weighed”; and “But … You measure everything you make; you count it, you weigh it. You make sure that everything is in perfect order [or, balance].”

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on The Wisdom of Solomon. (UBS Helps for Translators). New York: UBS, 2004. For this and other handbooks for translators see here.