R/W at MP, LHO deals, passes and opponents are silent the rest of the auction, which proceeds as follows.
1♣ 1♥
1♠ 2♦
2♥ 2nt
3♣
You could bid 3♥ now (or perhaps 3 artificial ♦s; if you do, is that still considered 4th suit or 5th ?), but that'll get you to 4♥ far too often. It's a new partnership, no discussion of whether 2nt followed by 3nt promises 5♥s, except possibly that a second suit over 3♣ promises a 5-bagger and that a direct 3nt would deny one. Having said that, I might have the same problem in a more established partnership as well. My problem now is that if partner's ♣s are decent such as say KJTxxx or even KJxxxx and ♥s relatively weak, 3nt might easily produce the same number of tricks as 4♥. Or say some other hand like KQxx xxx - AKxxxx, is an excellent 3nt, they might need to lead a ♥ to stop 12 tricks, but 4♥ makes only 10 tricks most of the time. But if his ♣ are weaker, 4♥ gives you time to establish them. Is there way to offer a meaningful choice of games to partner or should you bid/gamble 3nt yourself ?