By BARBARA CAUSEY LA FIESTA IN JUAREZ celebrates a fifth anniversary tonight with big plans ahead for the sixth year. The Crew Cuts, a quartet which made “Sha-Boom” Popular in 1954, are the current attraction. They will be followed by the Quintetto Allegro, five gentlemen who call themselves “Italy's Ambassadors of Melody and Humor.” The combination violin and comedy act will be accompanied by Hugo Avando, a baritone, and Mexico’s top singer. This program marks a return to the International emphasis. In No vember, Margaret Ann and the Ja-Da Quartet will appear with their 1920 Charleston style. This group follows another La Fiesta policy of featuring young and up coming talent; they were guests on the Perry Como show twice last season. The Holiday season will feature Homer and Jethro, a comedy team. The satirists of popular songs are big names in show business and will culminate a full year of well-known attrac tions. This tradition began last November with the appearance of the Kingston Trio. THE CANADIANS appearing now are Ray and Johnny Per kins, Pat Barrett and Rudy Mau geri. Their musical director who also gets into the act is Marty Jay. Although they introduced mod ified rock ’n’ roll with their 1954 hits, the group sticks to voice blends and ballads in their night club act. The RCA Victor record ing artists grew up together in Canada and became a vocal group in 1951. All are soloists with mellow voices and the act has an abundance of youth and Vitality. They don’t wear crew cuts. This is because the Crew Cuts with short haircuts look bald on stags and under a spotlight. And they are all in their early 20s. Efren and Mariano Valle of La Fiesta call the past and future a dream come true and they plan to keep bringing big names to the club.