Are my unacknowledged kafka messages dropped due to network latency? - asynchronous

Question

I have rdkafka producer written the following way, where localhost:9095 is tunneled to a digital ocean server in Germany with a kafka broker, whereas i, the localhost, am in New York.
I am noticing that at around ~150 miliseconds of thread::sleep(Duration::from_millis(150)) the last few of my messages stop being acknowledged by the callback (messages 8 and 9 for example),as if they didn't arrive. I know they did because i see the Kafka topic.
I'm wondering if my guess is correct that it is solely the latency between NY and Germany that dictates how long the broker takes to respond or if there is some config max.response.wait.ms setting i can set for acknowledgements to arrive sooner.
Of course if i increase the sleep time to ~200ms and higher i can see each message logged loud and clear. If i decrease sleep to 50ms the producer drops before any messages are sent and they never arrive to the topic... right?
let producer :ThreadedProducer< ProducerLogger> = ClientConfig::new()
.set("bootstrap.servers", "localhost:9095")
.create_with_context(ProducerLogger{})
.expect("Failed to create producer");
for i in 1..10{
let mut data = [0u8; 8];
rand::thread_rng().fill_bytes(&mut data);
println!("Sedndg msg with data {:x?}", data);
producer.send(
BaseRecord::to("rt-test")
.key(&format!("key-{}",i))
.payload(&format!("payload-{}",i))
)
.expect("couldn't send message");
// producer.flush(Duration::from_secs(1));
thread::sleep(Duration::from_millis(150)) // <--- Parameter to play with
}
Sedndg msg with data [da, 44, 1c, f0, 6, 1d, da, 9b]
Sedndg msg with data [37, 82, b2, 58, e2, 91, 40, 33]
Sedndg msg with data [8d, f8, 5c, df, 68, 12, a1, 26]
Sedndg msg with data [bd, 13, 7c, 81, 62, 5c, 93, 75]
Produced message key-1 successfully. Offset: 193. Partition :0
Produced message key-2 successfully. Offset: 194. Partition :0
Produced message key-3 successfully. Offset: 195. Partition :0
Produced message key-4 successfully. Offset: 196. Partition :0
Sedndg msg with data [d, 9d, 1c, 73, a7, 9f, b4, 2]
Produced message key-5 successfully. Offset: 197. Partition :0
Sedndg msg with data [c9, 1a, 3b, 8c, 31, cc, 84, f4]
Produced message key-6 successfully. Offset: 198. Partition :0
Sedndg msg with data [8a, 33, 26, 92, 2a, bf, d1, 7d]
Produced message key-7 successfully. Offset: 199. Partition :0
Sedndg msg with data [78, eb, e2, 41, 8d, b9, 29, 68]