All call ins are affected by increased costs if you don't tech. That isn't a reason to give an already strong unit a cost reduction (which is a buff). It is better than a standard OKW Panther which is why it should cost more.
Also in team games (esp 3s and 4s) you can sometimes be waiting on CP's but not resources. Hell in a 2's game yesterday with 2x <100 players I tech'd T4 and then got a CP out.
I have explained which tanks should be affected by the cost increase and why.
If you remember Easy and T34/76 saw a cost reduction when tech cost was required of them.
The C. panther higher price is only justified if other tank are around or by the debuff, having and a tech cost and significant higher price makes the unit not worth it in 1vs1.
The issue in higher modes has to do more with inflated economy and other factors and not the unit itself.
Fixing those factor is better approach.
CP gain in larger modes (3vs3, 4vs4) is slower and usually one has the resources to tech before one enough CP. You can check SiphonX thread about it.
Imo generally speaking aura units should be weaker that their counterpart but cheaper and their auras should scale with veterancy.
Finally C.Panther is not what this thread is about, so one should not focus on the suggested changes in the specific unit.