Commercial real estate broker here with 20 years specializing in restaurant and food service leases in the greater LA area. This thread hits close to home because I see this exact scenario play out regularly, and there are some negotiation strategies that can make a real difference.
First, regarding the leverage from the harassment documentation: this is your strongest card. In my experience, once a landlord receives a formal attorney letter with photographic evidence of interference with business operations, the dynamic shifts dramatically. I have been involved in negotiations where documented harassment resulted in the landlord offering a full buyout of tenant improvements just to avoid litigation risk. The key is making the landlord calculate that fighting you will cost more than compensating you.
Second, the Burbank relocation: make sure your new lease includes a comprehensive renewal clause, a right of first refusal on adjacent space, and clear language about tenant improvement ownership and removal rights. I would also strongly recommend a co-tenancy clause if you are going into a multi-tenant property, which protects you if anchor tenants leave and foot traffic drops.
Third, for anyone reading this thread for future reference: the time to negotiate lease protections is before you sign, not after. I always advise my restaurant clients to negotiate at minimum a 5-year initial term with two 5-year renewal options, a cap on annual rent increases (CPI plus 2-3 percent max), and an explicit definition of trade fixtures that covers all movable commercial kitchen equipment. These provisions cost nothing to include at signing but are worth tens of thousands of dollars when disputes arise later.