Update :
1) Ok, the Currency Switcher module created a mess… The (automated) conversion rate was wrong, which converted my USD gifts into EUR 0 gifts… that’s the reason the progress bar did not evolve (my goals are set in EUR).
Solution : I manually re-entered the gifts amounts through the back office, updated and the EUR conversion was back to normal.
2) Sooooo. : remains my question about manually updating a Goal progress bar. Tks.