How to prevent from slack connection error?( We had some trouble connecting. Try again?)

I’m working on a Slack bot. I’m using a model to get data from the user and using two functions (lambdas) to schedule events based on the data provided by the user, however every time I hit the submit button for the model, I get the following error: “We had some problems connecting.” Try again? ), and I believe this is happening because two lambda functions are being called simultaneously, causing the computing to take longer than 3 seconds to complete. Since calling both lambda functions simultaneously is necessary, how can I do this without encountering any errors?
I’m using javascript.

if (isPermission) {
    let privacy = setPrivacy(employee_id, bdDate, orgId, anniDate, DOB, BYear, token);
    let invokeAnni = Invoke(employee_id, orgId, Empinfo[0].Employee.firstName, action1, anniDate, Local, payloadData.user.id);
    let a =  Invoking(employee_id, orgId, bdDate, Empinfo[0].Employee.firstName, action, Local, payloadData.user.id);
    let update = botreply(payloadData.user.id);
    flag = 0;
    await privacy;
    await invokeAnni;
    await a;
    await update;
    return {
        statusCode:200
    }

}
else {
    let privacy = setPrivacy(employee_id, bdDate, orgId, anniDate, DOB, BYear, token);
    flag = 0;
    await privacy;
    return {
        statusCode:200
    }

}

invoke and invoking are two lambda function which i’m calling simultaneously.