TL is a kind of slippery idea anyway.

Because *historical* TLs aren't that good of a guide to what would
happen in the real world.

As an example "Roman" level tech *plus knowledge from higher TL
cultures* gives you a *very* different set of doable projects without
requiring much of a change in available tools.

For example, semaphore telegraphs are quite doable (the lenses for
telescopes/binoculars) are the hardest part). That alone is a major
change.

Heliographs are quite doable as well.

Limelights may be doable and that gives really long ranges for night
time messages (also nasty surprises for barbarians trying to sneek up
on the defenses of a fortified city at night :-)

Electrical telegraph is harder both because of the cost of the wires
and because keeping people from stealing the wire will be hard :-)

Crude radio (say spark gap transmitters and crystal receivers)  is
doable.

And that's just communications.

Pick just about any field and without changing that tools and
resources of X TL, you can get a lot of stuff that wasn't aviale
until Y or Z, just because nobody thought of it, or they didn't have
the theory to tell them it was possible.

Just importing "books" (or some sort of media and readers for same)
will result in TLs that don't much resemble history.

And yes, things like a commsat/weathersat network are really cheap to
buy and useful enough for folks to pay for willingly.

So that native guide may have a sat phone with GPS, and check the
satellite network for the weather that's approaching over the next
few days.

So without huge changes in culture (though you would get them
eventually) you can have some major surprises for characters from
higher TL worlds who don't stop to think things thru (ie a large
percentage of PCs).

So basicaly you can take a "historical" (or fictional) TL X culture
and throw in various higher TL items. Some are luxuries the rich &
powerful importeed. Others are cpommodities that are fairly cheap to
support and useful enough to put up with the limits of having to
import them and difficulty of getting them repaired locally.

Check out any third world nation, especially in the back country, to
see how this is playing out on earth.

This means you can have a lot of local culture/flavor, as well as
surprises.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com