It's difficult to see what you're actually setting because the Markdown formatting of the forum maybe replacing some of your underscores, or you could be using the wrong setting name. Please check Tip: Formatting code for the Forum for how to format Code for the Forum and use code formatting for your setting name & value please...
That said, I wanted to make sure that that on the relay you set _BESClient_Relay_NameOverride and the value should be the relay name as you want clients to resolve it. After the setting is applied, the next time that Relay checks in it should update the relays.dat in the actionsite and the new value should be selectable in the Console as a manual relay option - so if the setting is applied correctly it should be available within a few minutes.
For the _BESClient_RelaySelect_FailoverRelayList, that should be set on the clients that are failing to find a relay. The value should be a semicolon-delimited list of relay.domain:port;relay2.domain:port as described at List of settings and detailed descriptions
With the FailoverRelayList applied at a client, the client won't need to gather a new actionsite, won't need to see the updated relay list (with name overrides), and in fact won't even have to manually select the relay -- once automatic or manual relay selection fails, the client will 'fail over' to one of the relays in the FailoverRelayList client setting; each is tried, in the order specified, and only if they all fail to connect does the client then try the root server.
As far as the 'Last Fallback Relay' option, that does not require a reinstall, it requires running the BESAdmin tool on the root server and applying the Advanced Option for 'Last Fallback Relay'. For your case it's probably not necessary, the FailoverRelayList at the client is probably a better option.
I don't see that BESClient_RelaySelect_UseFailoverRelaxList is a valid setting at all, if you found that at some link I'd like to see because I don't think it's correct.