וְהִפְלָ֤א יְהוָה֙ אֶת־מַכֹּ֣תְךָ֔ וְאֵ֖ת מַכּ֣וֹת זַרְעֶ֑ךָ מַכּ֤וֹת גְּדֹלוֹת֙ וְנֶ֣אֱמָנ֔וֹת וָחֳלָיִ֥ם רָעִ֖ים וְנֶאֱמָנִֽים׃
l’Éternel donnera une gravité insigne à tes plaies et à celles de ta postérité: plaies intenses et tenaces, maladies cruelles et persistantes.
Rashi
והפלא ה' את מכתך THEN THE LORD WILL DISTINGUISH THY PLAGUES — He will afflict you with plagues exceptional and quite different from other plagues.
Chizkuni
והפלא, “He will make wonderful, in the sense of the plague being extraordinary long lasting.” The last letter of the word is an א, (not a .(ה
Ibn Ezra
The word your plagues has elements of the singular form and of the plural form, in combination. Compare, “this testimonies of mine that I shall teach them” [Psalms 132: 12].
Rashi
ונאמנות (lit., trustworthy, reliable), i.e. certain to chastise you — certain to perform the task entrusted to them.