While I agree that the first part of the OPs question is interesting, and would provide a peephole into how intuitional investors secure their crypto assets, the latter part concerning the call for traceability and the ability to follow their crypto investments around seems too much of a stretch for transparency. Corporations have a right to semi-anonymity too (yet not in front of their investors).
On the matter at hand, Tesla stated the following (SEC form 10k), without going into specific details:
Finally, as intangible assets without centralized issuers or governing bodies, digital assets have been, and may in the future be, subject to security breaches, cyberattacks or other malicious activities, as well as human errors or computer malfunctions that may result in the loss or destruction of private keys needed to access such assets. While we intend to take all reasonable measures to secure any digital assets, if such threats are realized or the measures or controls we create or implement to secure our digital assets fail, it could result in a partial or total misappropriation or loss of our digital assets, and our financial condition and operating results may be harmed.
See:
https://ir.tesla.com/_flysystem/s3/sec/000156459021004599/tsla-10k_20201231-gen.pdfThey acknowledge the risks, but do not depict their storage plan; at least that I’ve managed to find.
Microstrategy goes one small step further into unveiling their custody plans (SEC form 8k):
If we or our third-party service providers experience a security breach or cyberattack and unauthorized parties obtain access to our BTC assets, we may lose some or all of our BTC assets and our financial condition and results of operations could be materially adversely affected
Security breaches and cyberattacks are of particular concern with respect to our investment in BTC. While we hold the bulk of our BTC assets with established cryptocurrency custodians, a successful security breach or cyberattack could result in a partial or total loss of our BTC assets in a manner that may not be covered by insurance or indemnity provisions of our custody agreements with those custodians. Such a loss could have a material adverse effect on our financial condition and results of operations.
They cite custodians (not being specific as one would expect) and insurance by derivation (provided by the custodian under whatever fine print rules the agreement).
See:
https://www.sec.gov/Archives/edgar/data/0001050446/000119312520215604/d921849d8k.htm 
