He was in Mexico, but not Europe as far as I know. EW was known in Europe during his lifetime though; there is that marvellous quote attributed to Henri Cartier-Bresson in the '30s, "The world is going to pieces and people like Adams and Weston are photographing rocks!" (N.b. he denied saying that, later in life) Did EW ever photograph or show in Europe? I haven't found any info indicating that he did. And perhaps HCB knew about the U.S. west coast photography scene only though his own trip.
Edward Weston first attained international status during his pictorial period between 1911 and 1920. His work traveled to Canada, England and the European continent to numerous photographic salons. Other international showing of Weston's work include:
1930-Film un Foto, Stuttgart, Germany
1933-Exposition Internationale de La Photographic, Brussels, Belgium
1934-International Arts Theater, Singapore
1938-Musee de Jeu de Paunne, paris, France
1949-Stedelijk van Abbe Museum, Eindhoven, The Netherlands
1952-Cercle Photogrphique de Charleroi, France
With the exception of his travels to Mexico between 1923 and 1926, Edward Weston never left the United States. The vast majority of his work with eastern and southern locals were taken Between May 9, 1941 and January 20, 1942 during his "Leaves of Grass": travels through 24 states. Weston created 700 negatives during that period.
Walker