Synonyms of inadequacy in English:

insufficiency, deficiency, scantness, scarcity, scarceness, sparseness, dearth, paucity, poverty, shortage, want, lack, undersupply

paltriness, meagreness, niggardliness

sketchiness, incompleteness, limitedness, restrictedness

rare exiguity, exiguousness

incompetence, incapability, unfitness, ineffectiveness, ineffectuality, inefficiency, inefficacy, inexpertness, lack of skill, lack of proficiency, ineptness, uselessness, hopelessness, impotence, powerlessness

amateurishness, inferiority, unsatisfactoriness, substandardness

shortcoming, defect, fault, failing, weakness, weak point, limitation, flaw, imperfection, Achilles heel

loophole