This could be working as intended to avoid making the cards too strong. But the Rogue Lord card does not get bonus to him when you use a “Pirate Captain”'s ability to summon a Rogue card.
Rouge Lord card
Pirate Captain card
When a Rogue Lord card is deployed, each time a Rogue card is summoned from then on, the card gets a bonus to his power. When the Pirate Captain is used to summon a Rogue card with Mana instead of gold at a settlement or banner, the Rogue Lord does not get his power increased.
How to reproduce
Summon a Rogue Lord and Pirate Captain card
Take note of the current bonus attack on the Rogue Lord.
Use the Pirate Captain spell to summon a Rogue card from your hand onto the field.
The Rogue Lord does not gain any extra power.
The Rogue Lord gains power if the Pirate Captain spell is successful in summoning a Rogue card.