- tflatten -- With flattening procedures, there's always the question of
whether it flattens only one layer of lists, or all layers recursively.
This looks like it flattens all layers. I don't know if there are
standard names for these variants; I've used "flatten-once" and
"flatten-all".

- tsegment -- This operation is variously known as 'segment', 'group',
etc. Is one of those names preferred in Scheme as a whole?

- tadd-between -- This operation is variously known as 'interpose',
'delimit', etc. Is one of those names preferred in Scheme? If not, the
obviousness of "add-between" is nice :)

- tconcatenate -- Could this be 'append' for symmetry with tappend-map,
or is it deliberately called concatenate instead of append for a
particular reason? SRFI 1 has both append and concatenate; append is the
usual one featured in most Scheme programs so it's more familiar.

- tdelete-neighbour-dupes -- Would the American English spelling
"neighbor" be OK? Almost all Scheme code uses AE spelling.

- revery -- The identity value is not stated in the SRFI. According to
the implementation, the identity if #t, which is the usual one and
matches SRFI 1.

P.S. Linus, congratulations on your first SRFI :) Very good work!