«وَانْضَافَ إِلَى ذَلِكَ أَنْ يَصْحَبَ خَبَرَهُمُ إِفَادَةُ الْعِلْمِ لِسَامِعِهِ»
An additional requirement is that their report yield knowledge to the hearer.
This concerns the epistemic effect of transmission. Knowing that a report has numerous routes does not by itself prove that its content has become certain to the hearer. The total configuration must genuinely yield knowledge.
Distinction: Multiplicity is a property of transmission; certainty is its epistemic result. A report can be widely circulated without qualifying as mutawatir in the precise sense used here.