A few things to consider:
1. It doesn't matter what color the coolant is, as long as it is silicate and phosphate free it will be compatible with the BMW coolant. Color is just brand marketing. However, there MAY be changes in the additives which COULD cause issues since your bike has been used to living with BMW stuff for a long time. Considering the minor difference in cost I would stay with BMW brand - and you can get two complete changes out of a gallon. There are only a few manufacturers of coolant still in business anywhere in the world - they market all their stuff to affiliates who brand it.
2. Speaking of that gallon, dilute it 50/50 with distilled
3. Buying pre-diluted coolant is like paying 10X retail for distilled water for the "convenience" factor. It is SUCH a scam, designed only to increase profits for the manufacturer.
4. Make SURE you replace the radiator cap with any brand like "mini cap" which are common, especially in the EU. I forget how many bar it is but it should be stamped on the top of your existing cap. Once the old rubber gasket has taken a "set" it really should be replaced - since it can cause you all kinds of hell - as in micro leaks letting air into the system and almost impossible to find. Radiator caps are dirt cheap. Don't get taken in by paying 4X what it costs at the dealer.
5. You can EASILY fill the radiator from the top by snaking a length of clear vinyl tubing - attached to a funnel - without removing anything. Use clear vinyl so you can tell when it's almost full to avoid spills.
6. After you fill it burp or massage the lower radiator hose in order to purge any air bubbles that may have been trapped. You will to need to take the cap off several times after you've done this to check the level. Top off the radiator after riding and getting the engine hot enough to open the thermostat. (let it cool before popping the cap) You want absolutely no air in the system, or it will decrease the cooling efficiency dramatically.
6. It may be time for all new hoses and clamps as well. Once again cheap insurance and probably needed since you reported your initial leak at the junction with the connection. That particular hose should not be used again. BMW hoses have an extremely long service life, but they do degrade from the INSIDE first
- just like all other coolant hoses.