If the property was not homesteaded before they liened up, then you will have some problems with clear title when you try to sell or refinance. Best to lawyer up now and get homestead on file, just because you did not file homestead for tax purposes, does not mean it is not homestead. You need to discuss the elements of homestead with an attorney or do some research today.
If you were never served with the summons you may be able to file a Bill of Review in Texas to try and vacate the judgment. http://www.judgmentrelease.com/articles/Bill-of-Review-in-Texas.htm
My comments are not legal advice and are for informational purposes only.