Here ya go this works for me (eventho ignition turns it red, which might cause some performance issue in the designer, but should be fine in the client):
you can use css display:grid
try putting these styling into the flex repeater
{
"classes": "",
"display": "grid",
"overflow": "auto",
"grid-auto-flow": "column",
"grid-template-rows": "repeat(2,1fr)"
}
change the ‘2’ in “grid-template-rows”: “repeat(2,1fr)” to the number of rows you want
