The ''Horizons '84'' festival of new music recently finished at Avery Fisher Hall may have had some problems. However, the scope of the project undertaken by the New York Philharmonic was as ambitious as its execution was praiseworthy.
The quality of the selections was generally high, for which festival artistic director (and composer) Jacob Druckman deserves full credit. The Philharmonic organization must be commended for the undertaking - a costly affair with little hope, even at capacity, of making much money with the $10-a-seat admissions policy.
And the Philharmonic players, who were involved in five of the programs, seemed to rise to the stiff challenge of learning some 14 pieces from scratch. They responded to all the conductors with respect and care, even when the actual conducting was confusing, if not misleading - as in the case of composer Krzysztof Penderecki.
The festival opened with music by Hans Werner Henze and Penderecki, the composers conducting. Henze's 10-year-old master tapestry of a work, ''Tristan, '' impressed one on first listening for the quantity of ideas and the way they were woven into a whole fabric. Equally impressive was the unerring orchestrational skill that allowed those ideas to be communicated. Penderecki's First Symphony weds the ''sound'' of the 1960s to a traditional symphonic structure - on the surface radically modern but at the core deeply conservative. It has the semblance of excitement with little substance beneath the veneer.
It was fitting to open this sort of festival with a tribute to two such noteworthy European composers. Another revered member of the creative community, George Crumb, offered the world premiere of his work ''A Haunted Landscape,'' conducted by Arthur Weisberg. The 17 minutes of mood painting brought to mind extraterrestrial jungles and habitats of a science-fiction movie - and strove awfully hard to be instantly appealing.
The Crumb piece shared a program with Oliver Knussen's recent one-act fantasy opera, ''Where the Wild Things Are,'' with a libretto by Maurice Sendak from his book of the same title. Knussen conjures in his score the very monsters and gargoyles of Sendak's drawings in a 40-minute romp that owes a good deal to Ravel's ''L'enfant et les sortileges.'' The vocal writing is occasionally less lyrically attractive than expected. But all the scenes involving the wild things are enthralling. Even with some raucous amplification, the ebullience of the score always stood out, and Zubin Mehta (in his first conducting apearance here since last winter) exploited the uproarious aspects with his accustomed theatrical flair. Karen Beardsley projected her pixieish personality with verve as the boy Max who sparks this adventure.
Leonard Slatkin offered two impressive pieces on his program - Christopher Rouse's five minutes of orchestral lunacy entitled ''The Infernal Machine'' and Thea Musgrave's eloquent, superbly crafted ''Peripatea.'' Works by Robert Beaser and Donald Erb promised more than they delivered. Also on the program was Elliott Carter's Brass Quintet (expertly played by the American Brass Quintet) which, as with so much Carter, reads better in the program note than it sounds in the concert hall.
The final program was, ironically, the worst - in no way a festival closer. Departing Philharmonic assistant conductor Larry Newland set a low-key tone in works that had little to offer. Even the much-praised Harrison Birtwistle was represented by his uningratiating ''Down by the Greenwood Side.'' At least Tasmanian composer Peter Sculthorpe's ''Mangrove'' was an earnest attempt to evoke a specific mood and locale.
The highlight of composer/conducter Gilbert Amy's program was not his own intermittently attractive ''Shin'anim Sha'ananim'' but rather Pierre Boulez's ''Domaines'' for solo clarinet (the remarkable Stanley Drucker playing) and six groups of instrumentalists. It has all the earmarks of something hackneyed, yet Boulez's mind and sound-sense is so brilliant that the 32 minutes proved constantly engrossing.
Speaking of audiences, few programs drew much of a crowd. Now, a Philip Glass concert will sell out Carnegie Hall, and the Brooklyn Academy of Music was filled over 10 times for Glass's ''Satyagraha.'' If the word gets out that ''Horizons'' is stimulating and offers an interesting cross-section of today's music, it could become just as fashionable to attend ''Horizons'' as it is to be seen at the newest Glass premiere!