Before we can say whether "liberal conservative" is an oxymoron, we have to define the highly contentious word "liberal" and the somewhat contentious word "conservative". And that is no easy task.
What does "liberal" mean?
I do not know in detail how "liberal" is used in Switzerland, but I believe that, as in the English-speaking world, it is a word that several very different political groups have wished to use to define themselves because of its positive sound.
In 19th century Europe and America the word "liberal" would have been usually associated with support for laissez-faire economics and free trade, freedom of speech, extending the franchise, emancipation of women, ending of monarchical power, and opposition to the legal enforcement of religious rules. The common root, as the Latin derivation of the word implies, being liberty to do what you want. I wouldn't have said that 19th-century liberals necessarily opposed national identity (there are strong traditions of both liberal internationalism and liberal nationalism) but they certainly tended to oppose traditionalism and a patriarchal view of family life.
During the 20th century in the United States the word "liberal" kept the political associations above (and added others) but gradually lost its association with laissez-faire economics. Modern 21st-century US liberals now support a high degree of state involvement in the economy and actively oppose laissez-faire economics.
Because in Britain the word "liberal" was linked to the name of the Liberal Party, and later to the Liberal Democrats, it is not so often used to describe a general political philosophy.
In a further twist, the term "neo-liberal" has recently become a term of abuse (in contrast to the past history of everyone liking the word "liberal" so much that they all tried to take it for themselves). "Neo-liberal" is used by left wingers in both Britain and the US to describe in a hostile manner those who support the consensus that the best sort of economy is soft capitalist with state regulation.
My tentative impression is that in recent years the American meaning of liberalism has had an influence on mainland European usage, and that the older meaning of the word that you assume in your question (that of minimizing state intervention) has been diluted. European liberalism certainly seems less interested nowadays in matters of the economy and more interested in matters of personal behaviour.
What does "conservative" mean?
This ought to be straightforward. It means the people who want to keep things the way they are. The trouble is that the status quo that an early 19th century conservative wished to conserve was very different from the status quo an early 21st century conservative wishes to conserve. For instance the current UK Conservative Prime Minister fervently declares that he wishes to preserve the National Health Service, originally introduced by the Labour party and once seen by Conservatives as an undesirable socialist innovation.
There is a common thread within conservatism of respect for family, nation, religion and tradition, but how conservatives want to order the economy has varied almost as widely as it has for liberals. For instance the histories of both the UK Conservative and Liberal parties include multiple internal splits and see-saws over the issue of free trade versus protectionism.
Getting back to the liberal-conservatives, then, both parts of this term lack sufficient definition to contradict each other.
In practice it probably means a party that is "conservative" (in the sense of not socialist) on the economic front but wishes by the word "liberal" to signal that it is indifferent to traditional views about personal morality.