I used to play violin and this all makes complete sense to me.
1 tenuto, I would have interpreted this as stress unless told otherwise, a little more pressure put on the bow to bring out those notes;
2 a tenuto on the first note (of the tie) would make sense as it tells you how to approach (play) the very beginning of the note (not much use on the second note of the tie in this case, as the stress is applied at the first note);
3 also we are seeing these articulations in isolation. Sometimes it depends on what comes before (context) as to what might be intended (differentiation);
4 full value? (or intention thereof), yes this makes sense too with the staccato meaning to separate the notes as others have said because the slur shows to play the complete phrase in one bow length (equivalent to French horn, one breath) for that group of notes, stopping the bow momentarily (separation, staccato) to create each note sound.
You get a different sound if you play them with alternating bows (up, down, up, down) (also it can be visually disturbing … I know, let’s not go there!!)
5 slightly unrelated, if there was an accent instead of a tenuto, it would be interpreted differently, more pressure and quicker on the bow at the start of the note.
If there are any string players out there, feel free to disagree with me; it has been a while…!
Unrelated to the tie, the staccato-tenuto-slur is shown in Gould, p401.
BTW, I also used to play clarinet and its the same as for French horn, one breath, separate the notes so you can hear each, but stress and/or full value (depending on what is required). With this instrument, the tip of the tongue is moved onto the reed to momentarily stop the sounding of the note, with the breath continuing throughout (or intention of it doing so).
I’m just mentioning clarinet as well, so anyone wanting context can look up other instrumental parts.
Slightly unrelated (again) for (traditional) church organ there is no key velocity sensitivity for volume, so I was taught tenuto/accents are to be played with a slight gap from the preceding note and this could be indicated with a tenuto-staccato (no slur necessarily, although it presumably would indicate phrasing if it were there) and been understandable (although staccato unnecessary unless for some reason).
No explanation would be necessary as a footnote 
as it’s quite normal and understandable.