Solidres 4.1 – Change "1 Room, 2 Rooms" dropdown text to custom label

Hello,

we are using Solidres 4.1 with Joomla 6.

We would like to change the room quantity dropdown from:

1 Room
2 Rooms
3 Rooms

to:

1 Accommodation/Pitch
2 Accommodations/Pitches

We already tried the following:

Joomla language overrides (SR_ROOM, SR_ROOMS)
Editing default_checkavailability.php
Editing the German language file
Searching for the corresponding language strings and JavaScript files

None of these changes affect the dropdown.

It appears that the room quantity labels are generated elsewhere.

Could you please tell us:

Which file generates the "1 Room / 2 Rooms" dropdown?
Which language constants are used?
Is there an official way to replace "Room" with a custom term such as "Accommodation/Pitch"?

Thank you very much.