Can you link me to an example or inspiration source for my issue?
Try to look for some historical link between Poland and Romania. I wasn't good at history thus I can't give you any but there are many historicans on this forum, maybe they can help you out.
Of course you can go for the soft option and embroil the obvious: Polish national colours, Polish Emblem etc.
As for the folk culture you must know that:
1. it's a regional thing (Polish regions have their unique motives which not always pertain to whole Poland)
2. you might have difficulties to convey a folk motive in your graphic logo, unless you have a broad knowledge about Polish folk motives. For example I consider logo for Euro as not very good folk inspiration, it's barely recognizable what it is.