Unless they can cite actual examples then there is no reason to engage with such generic claims. Otherwise every claim needs to be investigated on its own merits. Sometimes we have throrough independent investigation that reveals what actually happened, sometimes not. From what we have seen in Ukraine one of three things is usually the case when they claim things like this: a) the story is completely made up, b) it was actually their side who did it (in the case of Syria we have numerous known instances of where the so-called “white helmets” were observed collaborating with terrorists to orchestrate attacks on civilians, detonating bombs and then claiming it was a Russian airstrike, then filming the aftermath in order to produce anti-Assad propaganda; Eva Bartlett who was present in Syria and is now in Ukraine has produced some excellent reporting on this), or c) the buildings in question were being used as military bases by militants and either had already been emptied of civilians or the civilians were purposely kept as human shields (again this is something that has also frequently happened in Ukraine, including with hospitals and schools, and we have both pictures/videos of soldiers in these buildings and witness testimony of people who were there).