Learn French: J'ai suggéré qu'il vienne avec nous. - I suggested that he come with us.

In modern everyday French, we no longer use the imperfect subjunctive to match a past-tense main verb. Instead, we use the present subjunctive for any action that happens at the same time as or after the main verb. Since him coming with us is the proposed future outcome of the past suggestion, the present subjunctive vienne is the correct choice today.

Would it be wrong to use the imperfect subjunctive here instead?

Grammatically, using the imperfect subjunctive (qu'il vînt) follows the traditional strict sequence of tenses. However, in everyday spoken or standard written French, it sounds extremely outdated and overly formal. Unless you are writing classic literature, sticking to the present subjunctive is exactly what modern native speakers do.

Why does suggérer trigger the subjunctive here in the first place?

The verb suggérer expresses a proposal, wish, or influence over someone else's actions. Because the action in the que clause isn't a stated reality but rather a desired outcome, it requires the subjunctive mood. This is the exact same logic used for verbs like vouloir (to want) or exiger (to demand).

Could I avoid the subjunctive entirely and use an infinitive instead?