Dear Katwijk, the number of relics you own would not be relevant in this case. It's requesting that you obtain 5 new Marble relics from anywhere on the world map, which may require from you to make progress on there. If you're not sure where you can find new Marble relics, you can hover on the provinces you have yet to discover, they will display the relics they provide. Then simply aim your effort toward there, solve the encounters in your way and scout the provinces to that area. The map is endless and the type of relics varies from province to province, but there are
always relics of any type to be obtained just by progressing on the map.
I do understand where you're coming from, but there is in fact no bug or issue with the quest. Though as mentioned previously, if you believe these type of quests can be improved in any way then you can propose changes in the
Ideas and Suggestions area. If you believe the quest text or hints can be made clearer, please report that in the
Text-related Errors area. Hope that clears up any confusion and enjoy the game.