If I stick that address into btgexp.com I get: Search found no results.
Me too, but that's btgexp.com's problem. You can see your address mentioned on btgexp.com when you look up the txid:
http://btgexp.com/tx/11f914b88918b734a879cddc0d911b1baf9916478cd2301065b6dca612992a1eI've confirmed these details on my own node with:
$ ./bgold-cli -rpcport=8339 decoderawtransaction `./bgold-cli -rpcport=8339 getrawtransaction "11f914b88918b734a879cddc0d911b1baf9916478cd2301065b6dca612992a1e"`
All I really want is to sweep it into coinomi. I used bitaddress.org (code running locally) to generate the address. The original private key did not work in coinomi, key not recognized if I remember correctly, so I used bitaddress.org - wallet details to convert to WIF private key. Key starts with 5Jay. Does this key need to be converted to something else, if so, how. I don't want to download the whole blockchain to use the core wallet.
I honestly don't know. I've never used Coinomi. I'm using a full node to manage my Bitcoin Gold.