One thing about The JL x RWBY movies I will say is that at least in some ways the story, designs and characterizations were better than the comics, The named JL/RWBY comic is completely different save for some design appearances for JL characters. Rather than a shared, cross-dimensional VR simulation, it takes place in an Alternate Universe where Justice League characters are re-imagined as parts of Remnant. It's the DC/RWBY comics where Team RWBY end up in the DC-verse, but that's about as similar as the plot gets.
Design wise I think the JL movies were cleaner and more distinct and underutilized characters are included, like Vixen. Barry Allen's design in the comics feels lazy; he's a turtle faunus but the trait is just some scales on his elbows. The movie Flash isn't great but it's at least more creative.
In the comics Batman has Bat Ears as his faunus trait, cool and useful, but Bat Wings are too and a lot more demonstrative for the small subplot of Batman experiencing real, tangible super-powers when he had none before, hit harder. Frankly speaking the second movie (the worse one) is closer to the DC/RWBY comic series rather than the JL comic series, what with Grimm running amock and the DC-design Team RWBY looking similar.
Weiss' dynamic with Bruce in the first movie is the dynamic she had with Cyborg in the comics with the latter being shifted over to Nora for some reason, which was the most cringe part; Ren being overly defensive and insecure and Nora being strangely petty against him, further increasing agitation from Ren.
TL;DR: Both comic series are a real mess, partially because of who wrote their stories in DC. The movies streamlined many ideas and visuals from the comics and tried to present them as cleanly as possible. They did a lot better than the comics did, even if the comics are more expansive (an advantage of having a wider volume to show scenes and dialogue than a few hours of screentime.