Synonyms for Proven:

adj.

authoritative (adjective)
verified, attested, supported, confirmed, documented, factual, authenticated, authentic, validated.
evidential (adjective)
authentic, established, substantiated, corroborated, counter-evidential, documented, Exhibited, Vouched, Exemplified, demonstrated, validated, evidential, supported, confirmed, Testified, certified, witnessed.
irrefutable (adjective)
certain.
proved (adjective)
established, demonstrated.
sound (adjective)
true.
tried-and-true (adjective)
certified, proved, tried.
true (adjective)
axiomatic, definite, veracious, gospel, true, honest, authentic, factual, right, certain, absolute.
undoubted (adjective)
assured.
valid (adjective)
tested, efficient.
well-founded (adjective)
substantiated.

n.

effective, helpful, high-powered, functional, practical, efficient, useful, worthwhile, valuable, operative. proven (noun)
evidenced, proved, well-tried, established, tested, tried, verified.

v.

ascertained (verb)
found out, double checked, ascertained, Audited, assured.
evinced (verb)
declared, documented, stated, demonstrated, witnessed, Exhibited, Indicated, supported, corroborated, confirmed, proved, validated, Betokened, authenticated, determined, deposed, certified, attested, observed, substantiated, Exemplified, Connoted, Manifested, Avouched, Testified, established, Evinced, Adduced, illustrated, Vouched.
experimented (verb)
tested, verified, researched, Experimented, benchmarked, Investigated, checked, Assayed, Probed, tried, analyzed.
proved (verb)
certified, confirmed, ascertained, determined, demonstrated, proved, established, verified.
substantiated (verb)
confirmed, corroborated, verified, authenticated, proved, supported, validated.

Other synonyms:

Other relevant words:
evidenced, effective, helpful, operative, functional, efficient, well-tried, practical, high-powered, worthwhile, valuable, useful.