Leanne Zaloumis, who is charged with trespassing on Cowell's west London property, spoke only to confirm her name and address - Brownhill Road, Catford.
She was remanded in custody at West London Magistrates' Court for her case to be heard by a crown court judge.
More top news
At least 27 high-rise blocks of flats in 15 local authority areas have failed fire cladding safety tests, the Government has announced.
New Zealand have beaten the British and Irish Lions 30-15 in the first Test in Auckland.
The company said its role was not to decide what was or was not compliant with local building regulations.