In November 2016 Google announced a new version of forward geocoder.
In the new forward geocoder the address components array contains only information that is relevant for address formatting in the country in question.
If I understand correctly, the administrative area level 1 is not used for formatted addresses in Česká republika, so this information doesn't appear in the address components.
The only reliable method to get admin area 1 at the moment is to execute a reverse geocoding request with coordinates from your first request and with result type equal to admin area level 1.
For example,
forward geocoder for 'nám. W. Churchilla 1938/4, 130 67, Praha 3 - Žižkov, Česká republika' returns 50.083244, 14.441828
Now the reverse geocoding with result type admin area level 1:
https://maps.googleapis.com/maps/api/geocode/json?latlng=50.083244%2C14.441828&result_type=administrative_area_level_1&key=YOUR_API_KEY
returns the following result
{
"results":[
{
"address_components":[
{
"long_name":"Prague",
"short_name":"Prague",
"types":[
"administrative_area_level_1","political"
]
},
{
"long_name":"Czechia",
"short_name":"CZ",
"types":[
"country","political"
]
}
],
"formatted_address":"Prague, Czechia",
"geometry":{
"bounds":{
"northeast":{
"lat":50.177403,"lng":14.7067945
},
"southwest":{
"lat":49.94193629999999,"lng":14.2244533
}
},
"location":{
"lat":50.0599268,"lng":14.5039935
},
"location_type":"APPROXIMATE",
"viewport":{
"northeast":{
"lat":50.177403,"lng":14.7067945
},
"southwest":{
"lat":49.94193629999999,"lng":14.2244533
}
}
},
"place_id":"ChIJi3lwCZyTC0cRIKgUZg-vAAE",
"types":[
"administrative_area_level_1","political"
]
}
],
"status":"OK"
}
UPDATE
There is also a feature request in the public issue tracker to add the administrative area level 1 in the response for Czech republic:
https://issuetracker.google.com/issues/35830929
Fell free to star the feature request to express your interest and subscribe to notifications.
UPDATE 1
Good news.
The feature request 35830929 is now marked as Fixed by Google.