Please tell me how to include for example the [TRANSACTION_ID] substitution in an email?

No, what substitutions are listed are the ones that are available. We've a pending feature ticket to add additional substitutions though. I've added topic to the ticket as well so please feel free to request any additional substitutions you may need that are not already available.

I've noted in the feature ticket your request.

I'm not pushing you, but could you tell us roughly when could we expect it to be ready please?

Unlikely anytime soon. You'll need to find a suitable workaround for the time being if you need those values now.

Is there a chance to sponsor the coding, so you could do it sooner please?

It's not a matter of money. It's a matter of time. We're preparing a new JP site, upgrading package builder to provide a new download platform, and other higher priority tickets in CBSubs are being dealt with (bugs before features). Once some of the more critical bugs in CBSubs are dealt with by Beat he can focus more on features, but for now it's important we deal with the bugs first.

Would you suggest a workaround?

You could use a CB Query Field to query for whatever information you're needing then substitute in the query field. That's about the only workaround I can think of at this time. The invoice address fields maybe able to substitute in using the following field names since they are stored in CBs _comprofiler table.

cb_subs_inv_first_name
cb_subs_inv_last_name
cb_subs_inv_payer_business_name
cb_subs_inv_address_street
cb_subs_inv_address_city
cb_subs_inv_address_state
cb_subs_inv_address_zip
cb_subs_inv_address_country
cb_subs_inv_contact_phone
cb_subs_inv_vat_number

Example as follows.

[cb_subs_inv_first_name]

The invoice number, etc.. are stored with the basket and payment items information and would need to be queried for.