I am certain this has been mentioned before, but as it is a significant issue, thought I'd mention it again.
In all areas of the Star Base, there are groups of Borg that go into overdrive. By overdrive, I mean that all of their actions happen at 2 to 3 times the normal pace of Borg activity. For example, when moving, they do not run like Medic Drones do. Instead, they walk like normal at an accelerated pace. The same is true for their melee attacks and weapons fire.
When I look at this during the mission, I feel like I am watching a movie set to fast forward. And once they go into this mode, you get overrun very quickly because of the mass of Borg involved and the fact that running isn't fast enough to get away.
It would be great if this got fixed, and I believe you already have the STF's under review.
The overdrived borg that your are referring to are the "patrols" or as the sto community calls them "wanderers." Best suggestion is to pull the group into a cleared area, then hunker down, pop all cds including pet abilities and get a dome up.
All drones summoning "proto drones" needs to be toned down too. In several B'Tran exploration missions (and Azlesa Expanse too), the Borg are too powerful. By summoning "proto drones", there are effectively double the number. My suggestion is to only allow the Medical drones to summon them, and do not let Proto Drones have shields. If they are proto-drones, they likely do not have all those fancy borg implants and technology. Also, those Proto Drones should have a different graphic. Some good examples are seen in Star Trek: First Contact.
It is a Benny Hill moment for me... I almost laugh when I see it and the crazy saxophone music starts in my head.. Definitely do not want to encounter these guys as an accidental group pull. Force Domes, cryo grenades or whatever you have should be used to wipe these out ASAP.
I try to flank them until I get all the aggro, so that the rest of the Team then has the Flanking position when they turn towards me... when they get close I run like a madman back to the group and pray the force dome is still up in the previous doorway and hope someone else will take my flanking position... By trading the flanking position between different players they can be wiped out quickly.
I had a group of four make it all the way to the last room. Manus of Borg (Rebecca Simmons) was difficult to access. I have a very hard time jumping around, and with the Tactical Drones constantly respawning, it gets very difficult to lower the shields and upload the virus in time. We did manage to get her on the central platform, but then she just owned us. I recognize that many players have been able to complete the mission, but even on RA, it was hard. I would suggest that once the shiled generator is detroyed, it does not respawn.