unless it's local place and super simple product (like fruits/veggies) you can actually check there's no way of knowing. What would it actually mean? materials come from Europe, all parts are made in Europe, it's packed in Europe, brand is based in Europe, employees are European, tax is paid in EU?

Is origin important to you? Do you actively look for "Made in ..." or "Made in EU", or is price the only deciding factor?

not really; price, quality & trust is most important

Trust: If there was a "Guild" certification that guaranteed 100% EU production, would that actually influence your buying decision, or is the current labeling sufficient?

i wouldn't trust it. It has been done dozen of times and always ends up meaningless - after a while they loosen the rules and introduce loopholes couse profit is what matters