If you post your TypoScript to create your language-switch, it would be easiert to help.
But the main prinziple would be:
# change the links you have defined, to add the QueryString Parameters
# so it will work with other extensions too
...typolink.addQueryString = 1
...typolink.addQueryString.methode = G
If you want to define explicit which params should be used:
# of define on your own which parameters should be added:
...typolink.additionalParams.append = COA
...typolink.additionalParams.append {
10 = TEXT
10.data = GP:tt_news[uid]
10.required = 1
# sanitize your url
10.rawUrlEncode = 1
10.wrap = &tt_news[uid]=|
# and so on
20 = TEXT
}
If you do not want duplicate parameters:
# check for duplicate parameters
config.uniqueLinkVars = 1