A bug in subplot()
is fixed since Scilab 2024.0. Here is a simple example with 2024.0:
clf
title("Titre général", "fontsize",4)
gca().title.position(2) = 1.09;
grey = color("grey");
for i = 1:4
subplot(2,2,i), plot(1:2), xgrid(grey), title(msprintf("Graphe n° %d",i));
end