Thank you for posting the scans of your covers.
The following are extracted from Postal Stationery of Mexico
, by Peter Bamert and others, 2018.
These envelopes were printed by Waterlow & Sons, London.
Envelopes with the 5 ctvo and 10 cvto indicium, 1899, from page 13...
The Types mentioned have to do with an embossing (or lack thereof) on the reverse that identifies the printer. To explain the different Types, the following extract is from page 11...
I don't see a sign of any embossing on your envelopes, but it may be that the scan simply does not show it. If not present, then you have the Type I. You can visually inspect these and other covers to see if one is present.
Your covers do not appear to be postally used, the cancellations strike me as being more of a favor type cancel. That puts them in a limbo between mint and used, and I have no insight as to how to assign a value.