In dependency, Bob's Ores are marked as being optional, meaning not required for the mod to work.
And while the mod loads properly, all crafting still requires said ores however there is now way to get them.

Bob's Ores should be moved from optional to required.

I have thought about this... but at the time, the ores of bobores were also used by other mods, like 5Dims, and most of the required ores were available from other mods.

it was made optional for that reason (you might have an alternate method for obtaining the ores)

is there a possibility to create the Galena Lead ore afterwards? (without recreating the game)

is there a possibility to create the Galena Lead ore afterwards? (without recreating the game)

If you started without ores mod and added it afterwards, you have 2 options.
1. Just explore further out, and the ores will show up when you generate new map data.
2. you can use a command
/c remote.call("bobores", "Regenerate")
The game will lock up for a few moments while the command runs and generates new ores, which is why its not done by default.