Back during his World Eaters arc, Fraction left Balder and Tyr wherever the World Eaters ended up.
In Journey Into Mystery, Gillen has Tyr serving as Hela's General and Balder commanding a force in Limbo against Surtur.
Was there something in the middle or are the World Eater's in Limbo? If that is the case how did Tyr get to Hel, and if it was Hela, why leave Balder in Limbo?
Short Answer: Its a hole (one of many) in Fraction's writing.
Long Answer: Most likely Tyr and Balder both ended up in Hel or at least that is what was implied. Gillen's work on Thor established Hela has a Valhalla for the gods under her dominion. She allowed Balder to lead a small force of warriors in limbo to try and keep Surtur at bay in exchange of Tyr being her general. There was no middle story to explain it, but that is what Gillen got with a few lines.