Indeed, the radius server cannot be changed via DB commands, because it's not setting which will be customized very often. In you case, you can override the default radius server with a custom template:
mkdir -p /etc/e-smith/tempaltes-custom/etc/chilli.conf
vim /etc/e-smith/tempaltes-custom/etc/chilli.conf/50radius
and put womething like
radiusserver1 1.2.3.4
radiusserver2 5.6.7.8
radiussecret your_secret
radiusauthport 1812
radiusacctport 1813
radiusnasid nas_id
radiustimeout 3
then signal-event chilli-update