Microsoft announced the end of Visual Studio LightSwitch in October 2016. The apps it produced still run — on a Silverlight or HTML client over WCF RIA Services — but the tooling is gone, so nobody can change them. The only people who can make sense of the generated code are the ones who built with LightSwitch when it was alive.
I built four production systems on LightSwitch — payroll, used-car wholesale, right-of-way appraisal, a food plant — and I have moved off it. The data model and the business rules survive; the generated client is what gets replaced, screen by screen, on a stack you can hire for.
Your Silverlight application has no browser left to run in.
Your records are in Notes databases. Getting them out is the job.