The Marketable Record Title Act (MRTA) eliminates matters of record recorded prior to a 30 year old "root of the title" (generally this means a warranty deed). The root of the title is different for each lot in your subdivision. Thirty years after the first lot in the subdivision was sold, the restrictions will start expiring on lots in the subdivision. The 50 year provision in your covenants is not relevant to the effect of MRTA. There are provisions in the Florida Statutes for reimposing covenants eliminated by MRTA. You should consult an experienced real estate lawyer in your area for help with this.
Disclaimer: This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.
The covenants could be preserved against your lot if any deed in your chain of title references the declarations by official record book and page number or they refer to a plat by plat book and page number and the plat references the declarations.
You have to look back 30 years or more. Start with your deed and work your way back until you come to the a deed that is at least 30 years old. If none of the deeds contain this information your covenants have probably expired against your property.
I suggest you consult a lawyer who is experienced in MRTA and HOAs to make sure.
This communication is not intended to create an attorney/client relationship. It is always recommended you consult an attorney in person to discuss your case. The Law Offices of Stage & Associates practices state-wide and represents homeowners and community associations. Please visit our website at www.stagelaw.com.