However the only use the Baha'i ever seem to have for Jesus is as a prop for Baha'u'llah. Perhaps to leave it there?
You can leave it where you choose to. Your observation is very flawed.
That observation would also be offering that Abraham and Moses were only a prop for Jesus.
It is also not considering that a sign of a true Prophet is that they will give testimony to Jesus.
Thus I share Baha'u'llah's testimony.
"Know thou that when the Son of Man yielded up His breath to God, the whole creation wept with a great weeping. By sacrificing Himself, however, a fresh capacity was infused into all created things. Its evidences, as witnessed in all the peoples of the earth, are now manifest before thee. The deepest wisdom which the sages have uttered, the profoundest learning which any mind hath unfolded, the arts which the ablest hands have produced, the influence exerted by the most potent of rulers, are but manifestations of the quickening power released by His transcendent, His all-pervasive, and resplendent Spirit.
We testify that when He came into the world, He shed the splendor of His glory upon all created things. Through Him the leper recovered from the leprosy of perversity and ignorance. Through Him, the unchaste and wayward were healed. Through His power, born of Almighty God, the eyes of the blind were opened, and the soul of the sinner sanctified.
Leprosy may be interpreted as any veil that interveneth between man and the recognition of the Lord, his God. Whoso alloweth himself to be shut out from Him is indeed a leper, who shall not be remembered in the Kingdom of God, the Mighty, the All-Praised. We bear witness that through the power of the Word of God every leper was cleansed, every sickness was healed, every human infirmity was banished. He it is Who purified the world. Blessed is the man who, with a face beaming with light, hath turned towards Him."
John 15:26-27 "But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me: and ye also shall bear witness, because ye have been with me from the beginning."
All the best.
Regards Tony