Blesta doesn't set a specific port when creating the server unless you provide that information (or it is already available from the package) when the service is created. Instead, Multicraft determines the next available port based off of your Multicraft settings and any other servers that are currently setup, in order to avoid duplicates. Perhaps your starting port number is not 25565 in Multicraft, or you have multiple Multicraft servers on that IP such that new servers get assigned a different port? I would need to see module log information to know more.
Could you clarify? The log you've included looks correct--simply creating a server. There should also be several subsequent logs, and if you have an available dedicated IP setup under [settings] -> [Modules] -> [Multicraft] that was set for that service, you should also have a log entry regarding updating the server to use that dedicated IP. For example:
http://domain.com/multicraft/api.php|updateServer
a:3:{i:0;s:2:"78";i:1;a:2:{i:0;s:2:"ip";i:1;s:9:"daemon_id";}i:2;a:2:{i:0;s:13:"123.123.123.123";i:1;s:1:"1";}}
That log shows the IP being set to 123.123.123.123 and the daemon ID set to 1.
Search the page for ip and you should find that log entry indicating the dedicated IP was set.
The last log in the list contains the information set for the server as given by Multicraft, which should contain the same IP. For example:
http://domain.com/multicraft/api.php|getServer
s:353:"{"success":true,"errors":[],"data":{"Server":{"memory":"256","start_memory":"0","port":"25580","id":"78","name":"Minecraft Server","ip":"123.123.123.123","dir":"server1","world":"","players":"10","jarfile":"","autostart":"1","default_level":"10","daemon_id":"1","announce_save":"1","kick_delay":"3000","suspended":"0","autosave":"1","jardir":"daemon"}}}";