But how could that happen?
In the RARR earthmap, after having played two very long testgames and seeing the problems, that the placement of the Celts on the map is triggering to many other European civs, I set the Celts to be not playable, deleted their starting location on the map and limited the number of civs to 30 - but it seems, that this was not enough. When deleting the Celts completly from the list of civs, this causes some other heavy distortions in the game (p.e.wrong starting locations of civs, when these are fixed, wrong units some civs can build). So at present I try this solution, that hopefully will fix the situation: The Celts will receive their own starting location again in Irland and the landbridge in that map between England and Irland will be cut down. The Celts will still be set to be not playable by the human player.
Here the old setting in the editor:
In long terms, the Celts will be replaced by another civ (may be Maori or Indonesia), but this will need some time, because at present the focus of my modding time is on WW2 Global Gold and SOE.
There are some things on the worldmap biq, that are not working as expected. When starting the 480 AD save file in Multiplayer mode, there was an UN election, so no civ had built the the UN or the League of Nations. The starting place of the Celts in the south of South America is one of the places the AI likes to start the Celts, but the AI mostly starts them in the south-east of Australia. When looking at the list of GWs after starting with the 480AD save file, the Great Lighthouse was built by the Celts in Pyrenne. It can be, that the game for each civ eliminated in the game, started a new Celtic civ, when the 'respawn eliminated civs option' is enabled.
Edited: When having a look at the screenshot, the time scale must be adjusted, too
... and tjs282 is right about the building restriction of the Great Lighthouse.