What other problems, apart from accent, can a receiver experience when attempting to listen to a sender?
This sounds like a question about effective speech communication. The terms "sender" and "receiver" are common in public speaking courses. All kinds of things can get in the way of a person receiving the speaker's intended message. These "things" interfere with the communication process and are commonly referred to as "barriers to effective communication."
You are correct that a speaker's accent could be a barrier for the listener. Another barrier for the listener might be the speaker's use of jargon. Jargon is special words or expressions that are used by a particular profession or group and are difficult for others to understand. For example, people that are not educators are often mystified when I use the term "pedagogy."
Another obstacle for a listener might be something as simple as another person trying to talk to the listener. It's very difficult for a receiver to effectively listen to two speakers at the same time.
One of my favorite barriers to effective listening sounds ridiculous at first. "What does the speaker look like?" A listener might not be paying much attention to what the speaker is actually saying if the listener is spending more brain power processing a particularly distinctive appearance.
A receiver might not be listening to the sender that well if the listener has something else on his/her mind. It could be something as simple as needing a bathroom break, or it could be something as serious as marital/relationship problems.
Another problem could be that the listener is biased in some way against the speaker. It could be race related, political affiliation, gender bias, and/or a preconceived notion about a topic.
There's also the possibility that the listener feels that the speaker is ignoring the receiver's side of the room. If the speaker isn't effectively engaging the audience through non-verbal communication, a receiver has the tendency to begin tuning out the speaker.