The rewritten BIP can be found at https://github.com/craigraw/bips/blob/master/bip-wallet-labels.mediawiki

It is perhaps simplest to understand it by looking at an example export:

{ "type": "tx", "ref":"f91d0a8a78462bc59398f2c5d7a84fcff491c26ba54c4833478b202796c8aafd", "label": "Transaction" }
{ "type": "addr", "ref": "bc1q34aq5drpuwy3wgl9lhup9892qp6svr8ldzyy7c", "label": "Address" }
{ "type": "pubkey", "ref":"0283409659355b6d1cc3c32decd5d561abaac86c37a353b52895a5e6c196d6f448", "label": "Public Key" }
{ "type": "input", "ref":"f91d0a8a78462bc59398f2c5d7a84fcff491c26ba54c4833478b202796c8aafd:0", "label": "Input" }
{ "type": "output", "ref":"f91d0a8a78462bc59398f2c5d7a84fcff491c26ba54c4833478b202796c8aafd:1", "label": "Output" }
{ "type": "xpub", "ref":"xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8Nq...", "label": "Extended Public Key" }

If you want, you can make a 3rd party JSON-Lines to CSV generator to interface with your original design goal of business editing of label spreadsheets.

I guess a purely software-to-software oriented format could also facilitate writing a simple script that generates an excel file or some other human-friendly representation.