My suggestions would be (If possible. Also feel free to not add these if u dont feel like doing improvements, still its kinda good to spend time.) Also if its not possible, dont do that. Just dont torture yourself ok

So, well. Like i said before, I have few suggestion. Like small details such as speech bubbles on top of people's concept - For example. A guard catches you or understands your intents and says "Hey! What are you doing?!" Or "Hey, you're not supposed to be here!" if you go in without disguise and a guard sees you before the guard is alerted. Also when your guns are visible, they should say "What the?!" and perhaps more dialogues to your creativity.

For the manager, when you approach the back room after luring him there, he should say something like "Here you go sir."  (since our character is apparently male). And maybe 2 guards should follow the manager to that room and wait behind him in the case something happens just like Withdrawal from Entry Point. (The count of guards to follow the manager should be based on the game difficulty, you know better)

Thats it kinda. I have some more but I don't feel like yapping and giving you a headache mkay. If its not possible, youre free to give up