I know I've been quiet lately, but I just wanted to let everyone know I'm still receiving and noting these bug reports, so keep it up!

Reporting a bug where Mercurial Flow being added causes the Power Attack multiplier to increase to 2x when using a two-handed weapon, as opposed to just increasing the multiplier to 1.5 when using an off-hand weapon.

Been really quiet for a while now, you doing ok?

It's slow going, but I'm still working on USoP.

Not sure which is causing the issue.

Battle Dragon's Stance (Thrashing Dragon, Level 3) in the Community Package reduces two-weapon fighting penalties by 2.

Balanced Blows (Dual Wielding) in the Spheres of Might package, reduces the penalties by half, when using Dual Attack.

Incidentally, with Weapon Groups on the Weapon Tab, Balanced Blows modifies the numbers for full-attacks which is probably the best we'll get since Hero Lab isn't going to display just two attacks.
It's up to the user to only use the first attack with each weapon.

However, with both Battle Dragon's Stance (enabled) and the Balanced Blows talent known, the penalty with the Two-Weapon Fighting feat and either 1H/Light or Light/Light weapons is reduced enough to grant a +1 bonus through the halving of the -2 penalty and removal of the -2 penalty.

It's the interaction of two different products; either works fine on it's own.

It's probably because the two don't actually combine.
Normal Two weapon fighting, which Thrashing Dragon modifies, is a full round action

The Dual-Wielding sphere works by giving you a 2nd attack when you make a Attack Action (which is a Standard Action)

So the one is modifying a Full round action and the other is modifying a Standard Action.

I know they shouldn't stack.
It's how Hero Lab is displaying them though.

It is giving the bonuses from both options to the full attack action.

A relatively minor bug I thought I'd bring up. I just recently purchased Champions of the Spheres and was building an animal companion build. The Martial Beast archetype does properly apply the proficient practitioner progression, as expected, but it does not add Extra Combat Talent to the list of Animal Companion Feats. I can still add it, of course, but it does throw a validation error.

I guess I'll mention another validation problem I've encountered. The Canny Hunter Martial Tradition grants a bonus talent from either the Equipment or Scout sphere. It has a drop-down to choose which talent to gain, but when an equipment talent is then added (in my case, Expert Reloading), it flags for validation because I do not have the equipment sphere (which should not be required when granted by the martial tradition). Huntsman training, which is explicitly added by Canny Hunter, does not get flagged.

Painted Savage?
 

I'm playing a Barbarian with the Painted Savage archetype from the Highlander's Handbook in a new game, how can I get it in Hero Lab?