Not sure if this limit is hard for all the bots, but it's good to have a reference of avoiding more than 30 messages per second. https://telegram.org/tos/bot-developers#6-2-5-broadcasting-messages-with-stars

Another suggestion:

1. Use a VPN to avoid having multiple accounts from the same IP.
2. Use one account to consume data from the first channel and a different one to produce into the second one.
3. I considered having the consumer and the producer bots running into different VPS, communicating via API.
4. Rate limit of 20-30 messages per minute.
5. Avoid using virtual numbers?