I'm intrigued what you mean by these examples, Lucius.
No more travels
I guess I can understand but only if he had arcane connections to every place he wished to travel instantly, otherwise he'd have to first actually sacrifice the seasons to go such places and get the necessary connection (rock, stick, device whatever) then bring it back home, then spend a season fixing it in his lab.
As you can see, unless the magus intended to sacrifice about 5-10 years of saga time (troupe permitting as well) just to wander around to places he "might" want to be able to teleport to at some future point, I think this is easily kept within balance.
Extreme combat power
In what way? LoH is a transport spell for the magus him/herself, not a combat spell and not a spell that would allow for an X-men "Nightcrawler" type popping in and out around an opponent.
Please do enlighten us how your player figured he could use the spell offensively.
More seasons
In a limited number of cases as mitigated by simply limiting the number of places he/she can teleport to (as per my response to your first point), sure. But then, in those instances where it is a valid means of getting there, why not save the time to apply to other tasks?
No need for supplies
Can't see this aspect either really. So your player thinks he can zip across Europe and others are just going to provide for his every need?? LoH doesn't preclude the possibility that you might be left stranded somewhere waiting for people to get back to welcome you in. Being without supplies is simply an open invitation for the prudent SG to teach silly players a valuable lesson in common sense.
Let's also not forget that LoH even if claimed to be used to pop between covenants would still have to take into consideration:
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The leaping magus was indeed welcome anytime he/she wished to just turn up (not likely for most covenants).
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The fact that whether or not one was generally welcome at another covenant, the nature of Aegis of the Hearth demands that a visiting magus have a token every time they visit otherwise the spell would just fizzle against the target covenant's Aegis and either essentially fail from the moment of casting or leave the magus flat on his/her butt outside the target location (god help the magus if his destination was situated on the top of a steep mountain cliff) lol.
No need for a base
So, your player also thinks that the acquisition of one convenient transport spell equates to no longer needing a home covenant or home lab? To my mind, another open invitation for the discerning SG to teach the player another lesson in common sense...
SG: "Fine Joe, so what do you do this season?"
Joe: ooh I want to create that next cool rego spell Ive been thinking about
SG: Ah, so where precisely do you plan to conduct this research since you no longer have a lab or a lab total lol.
Basically I see no reason why one spell should have unbalanced your saga so long as you play out the consequences of such ridiculous abuses of it.