It is from en-us source of WXP, WVista and W7 (both x64 and x32). Additional cs-cz MUI is standalone language pack installed later on en-us system.
Only thing, what English user should do, is to enter Pinball directory ( \Program Files\Microsoft Games\Pinball) and:
-rename pinball.hlp and pinball.chm to pinball_cze.hlp and pinball_cze.chm
-rename pinball_eng.hlp and pinball_eng.chm to pinball.hlp and pinball.chm
(It is Pinball help files only not UI interface of the game - UI of this game is always English.)
So you will always get English interface under English system.