Here is a VERY ROUGH AND AWFUL draft of what a crawl could look like if placed before the flashback:

The loathsome Galactic Empire continues
to rule the galaxy with absolute power. It’s development of
a new superweapon, the DEATH STAR, has now has put
the galaxy in utter peril.

Director Orson Krennic has overseen the weapon’s
development with the help of his friend, Galen Urso,
an imperial scientist who studies in the
field of Kyber crystals.

When Urso learned of what his research was
Really being used for, he fled the empire to the
Planet of Lah’mu, to seek refuge and peace
From the destructive intentions of the Empire…