Hi there! Let's say I have a table A and a table B. Table A is documented but table B is not. If I declare manualy within datahub that the lineage is A -> B, shouldn't B inherit the descriptions of table A in those columns that have in common table A and B?

This is something that is not currently supported out of the box, but you could build this easily using the actions framework. We have plans of building this, but it will probably be in the next 3 months.