If you have a CSV with numbers with dots, Calc will change it into commas
Steps to Reproduce:
1. Open a CSV with number with dots
2. Save it
Calc changes with dots into commas, and if you save it, it will change them into commas in the file, which is pretty stupid to do in a CSV
The number format should be preserved.
User Profile Reset: No
OpenGL enabled: Yes
Build ID: 00(Build:0)
CPU-trådar: 8; Operativsystem: Linux 5.7; UI-rendering: GL; VCL: kf5
Locale: sv-SE (sv_SE.UTF-8); UI: sv-SE
Imported numbers and dates are displayed with the formats of the current locale, which for you is Swedish (sv-SE) that uses comma as decimal separator. This is expected and normal behaviour. Saving to CSV uses the locale settings of the cells, which normally is expected by users.
To force a dot decimal separator you can assign number formats of a locale that uses dot as decimal separator, for example English-UK (en-GB), to the data after import. Or before or after import set the overall locale to an English one under Tools -> Options -> Language Settings -> Languages, Locale setting; which switches all display formats' default locale.
However, I agree that when exporting to CSV an optional target locale could be offered to override the cells' number format locale(s).
It should automatically use the same locale for exporting that it used for importing.