There is no security/privacy risk with the
luci-app-openvpn for configuring the OpenVPN client. All it does is writing the configuration in a format that can be parsed by
uci (backend). Such would (likely) be the same if integrated with the Foris frontend.
It still would require the user to understand the implication of the various settings, that is unless the user prefers to utilize the client settings furnished by the VPN provider without digging into the meaning of the various settings.
Foris integration would be rather a convenience by not having to login into LuCI unless it would offer the option to import client settings furnished by the VPN provider, as pointed out by @Pepe, and thus make a difference in convenience from LuCI.
If there was integration for the OpenVPN client into Foris than the other VPN client solutions should probably be intergrated too since VPN providers not only offer OpenVPN.