What do you do if the emotional impact of a film falls flat?

There have been several times where I've read a script and looked at the arc of the character I am playing and even before shooting begins I'll notice holes in that arc and will schedule a meeting with the director to voice my concerns and usually it's something that both the writer and the director has overlooked... Then we will sit and either revisit the script to make changes as I'll already have my own notes to express or even write a scene that will make the story flow much better... I believe it's in the interest of the whole production to do this and usually your come out the other side with a better story...

IMO, you have three options (listed in order of ascending complexity). Assuming you have competed production, and are into post production: 1. You can attempt a re-edit / rewrite in post. If this goes "nowhere", 2. You can recast and or reshoot. If that doesn't work, 3. Congratulations! You've just achieved the entry point of about HALF of all film festival submissions. (per #3, I've screened for festivals; this may be an understatement) Don't give up: You DID complete your project, which is promising. Release it anyway, because who knows? Audiences might still see something in the film that you are unaware of (it's happened before). Do seek competent assistance before embarking on your next project, however. Film editor of 3 decades.

Enhance a film's emotional depth by revisiting the screenplay if audience response is lacking. Look for opportunities to develop character motivations and conflicts more fully, focusing on visual storytelling to convey emotions effectively. Evaluate the stakes and relatability of characters' journeys, seeking input from a script doctor or fresh perspective to tighten the narrative and enhance emotional arcs.

Pacing is a strong requisite when making a movie as this dictates whether it will be a success or a failure... If you have a real passion for films you should have an encyclopaedia in your memory of films that you've watched that you can draw upon and offer solutions to the pacing... Usually this means looking at another production which closely resembles the pacing that you want to achieve and then to analyse and adapt what works to your production... In short to explore other film makers work and see how they used pacing to create a successful product...

There is a lot of truth behind the cliché "A director directs and an actor takes over..." A director can give you the pacing and the tone of the film and then it's the actors responsibility to deliver a performance which equals or outperforms the directors expectations... As an actor you usually have 2 maybe 3 takes before they move on so its important to bring your "A" game... Expect re-shoots or ADR where you have a second chance to give a performance that you may of missed on the day... They may even want to change the tone of the character after they have edited everything and realised something is not working... The other cliché is if the film is successful the actor will take the credit and if it bombs they will blame the director...

Giving and taking feedback is one of the most nuanced processes in the creative world. It is two individual POVs connecting on a path, and there is a give and take, one must approach the material with kindness and see these moments as opportunities.

Always go back to the story. If the story isn't crystal clear, rock solid and coming through in every shot, frame, cut, costume, location, etc. - then ask yourself why it's not taking the front seat. And hey, at the end of the day, not every project will be perfect. Once you've released as close to perfect as you can get it (within a realistic timescale - with a hard deadline, else you'll be working on it forever!), release it. Show the world, and be open to hearing what the world says back. Your next project will have all those bits you and the world love, and hopefully all those bits you and the world hate won't come along for the ride again.