As far as Janacek's concerned, he at first struggled with them -- no Czech composer before him had really bothered with them.
I wonder if Martinu might have picked up ideas directly from Smetana, though? Czech's similar enough to Russian that I can understand around 60% of it, but the stress-patterns are completely different. (Just one example, from HOUSE OF THE DEAD - when the Prison Governor orders that Goryanchikov's fancy clothes should be sold off, he says "PRO-dat!", whereas the same word in Russian is stressed the other way as "pro-DAT'").
Even so, I haven't noticed that Smetana (whose operas appeared in the period 1866-1882, and is therefore the preceding generation to Janacek) is struggling to set Czech librettos?
Unless I've misunderstood Tyrell's biography of Janacek seriously, I gained the impression that Janacek struggled for his entire career to emerge from Smetana's omnipresent shadow in the world of Czech music, and that Smetana's works were continuously in the repertoire of all opera theatres in the country? (Of course, we have to be careful to remember that Czechoslovakia didn't come into existence until 1918, only ten years before Janacek's death).
Although perhaps "rightly" we've posthumously granted Janacek the pre-eminence he deserves, I have the impression that Martinu's models, and the music that he heard most frequently in the opera-house, would have been largely Smetana's works? And for all my love for LJ, I have a sneaking regard for DALIBOR, LIBUSE, DVE VDOVY and HUBICKA, not to mention the only work of Smetana's now much played outside his home country, BARTERED BRIDE. They are very fine works, and we ought to be careful not to dismiss or pass them over merely because they caused poor Janacek such difficulty in getting his very different works staged
I'm not sure how much Martinu might have been influenced by Dvorak, though? Certainly RUSALKA has become successful, but it's one of the few which have. Dvorak's earlier works suffer from a fatal longwinded tendency to over-the-top grandeur and undigested Wagnerisms - anyone who's sat through DMITRIJ will know what I mean? The result - in relation to the question asked in this thread - is a tediously melodramatic declamatory style in which cardboard characters recite cod-heroism in ye olden style. It was only at the end of his career that he dropped writing this kind of
folie-de-grandeur and did the opposite - embracing the world of weeds and seashells by way of ridiculing the stuck-up pomposity he'd once promoted as an ideal? Even so, the charming conversational style of vocal writing that Martinu achieves so well doesn't seem to have roots in either DMITRIJ or VANDA, or amid the water-goblins and sprites of RUSALKA either.