Che and the Cuban revolutionaries were not adventurists in either case because their primary strategy was in building a base of support among workers. Adventurists only do violence, with no attempt at building a base or community outreach. The same was true of Che's efforts in Bolivia, he was trying to build a local base of support first and foremost.
To add context, as based as it was, the recent assault on the Israeli embassy was adventurist in essence because it was disconnected from any greater project, and had no association with the people in general.