You are right - I see the issue now. To me, that looks like bug, and I made a ticket for it.
{
"CreationDate": "2018-10-31",
"Commands": [
{
"Command": "store",
"Target": "fast",
"Value": "!replayspeed"
},
{
"Command": "open",
"Target": "https://a9t9.com/kantu/demo/storeeval",
"Value": ""
},
{
"Command": "storeEval",
"Target": "new Array ('cat','dog','fish','dog','??','frog','?','dog','??','horse','??elephant')",
"Value": "names"
},
{
"Command": "store",
"Target": "2",
"Value": "num"
},
{
"Command": "storeEval",
"Target": "storedVars['names'][${num}]",
"Value": "myrandomname"
},
{
"Command": "echo",
"Target": "in array is ${myrandomname}",
"Value": "blue"
},
{
"Command": "storeEval",
"Target": "storedVars['names'][${num}] = \"Hello World!\"",
"Value": "notused"
},
{
"Command": "storeEval",
"Target": "storedVars['names'][${num}] ",
"Value": "newname"
},
{
"Command": "echo",
"Target": "in array is now ${newname}",
"Value": "green"
}
]
}