[Assuming you mean Baldwin IV and his leprosy, as you mention 'delapidating injury']
Well, considering his constant wars, it wouldn't have been surprising if he'd been killed or maimed in battle. The Battle of Jacob's Ford in 1179 was a masterpiece by all accounts, and it has to be admitted that managing to both ford the river and defeat Saladin's force was really rather impressive. He did get lucky with Saladin being captured in the battle, allowing him to march on Damascus and giving room for Raymond and Bohemond to capture Harim in Syria. If he hadn't been captured, the Muslims could probably have successfully prevented the fall of Damascus, even after the battle, and Jerusalem would have been stuck on the coast.
Honestly, without Baldwin's victory at Jacob's Ford, the crusaders probably wouldn't have captured Damascus and Egypt wouldn't have fractured away from Ayyubid rule. That means that the Kingdom of Jerusalem would have been severly constricted and probably confined to the coasts.
As to the language, it wasn't until the 14th century that the crusader dialects really started to diverge from their mother-tongues, becoming the Normaunt [spoken primarily in the Principality of Antioch] and Frankeis [spoken throughout the rest of the crusader kingdoms] dialects of today. Without the larger and more stable Kingdom create by Baldwin, the Latins in Outremer are going to remain heavily reliant on Italian and Greek aid. I'd expect Greek to be even more influential that it was OTL, so that Frankeis, not just Normaunt, has a whole load of Greek loan words too and maybe even some of Greek's grammatical structure. I'd imagine there would be a lot more Italian loan words too, there are still a few today OTL, but there could have been a whole load more. The Italians got kind of left out there OTL. Oh, and conversely Arabic would probably be far less of an influence without all those extra Muslim settlements inside the Kingdom.