iOS, iPadOS, Activities, and language switching; bug or by design?

Hi there

First of all sorry on my english.
Hopefully I will be able to explain my problem.

I use Iphone XS and Ipad Pro second generation.
On my Iphone i have installed ios version 15.1
On my Ipad i have installed Ipad Os 15.1

My iphone and ipad are setuped as follows
Settings > General > Language & Region > Prefered Language
English en-US is prefered and Croatian (Hrvatski) is secondary (second on the list)

Settings > Accessiblity > Voice Over > Speech
Default Language is Alex (en-US) and in rotor languages i have
Czech (closest to Croatian)

Since I'm using email app most of messages are on Croatian but 10% of them is on english.
Its logical to setup an activity wich i did.

I created an activity that will activate when i use mail app.
And it works great. Once i open my mail app the czech voice is automatically activated.

Now we get to the issue.
As i mentioned above I also have mail messages that are on english.
When i go to english mail message I use rotor, navigate to language, it says "default english"
but it stays on czech. There is no way to change language.

If i delete activity I can use rotor in my mail app to choose language/Voice I wish

Also I use Safari for mostly english sites and its also logical to create an activity :-)
So i created an activity to activate Alex voice when i use Safari.
Everything works fine but problem starts when i go to a site that uses croatian language.
I again try to use rotor navigate to czech but voice always stays in english.

If i delete activity I can change voice using rotor in safari.

The problem is on my Ipadd as well since activities are synced.

Is this by design or a bug. To me it seems as a bug.
Can anyone reproduce this issue as well or can anyone help me to resolve it.

Many thx!